US2014221122A1PendingUtilityA1

Bend-twist coupled golf club shaft

45
Individually held — no corporate assignee on recordPriority: Sep 6, 2011Filed: Sep 6, 2012Published: Aug 7, 2014
Est. expirySep 6, 2031(~5.1 yrs left)· nominal 20-yr term from priority
Inventors:Peter IfjuJarrod Mark BonsmannDavid A. Jenkins
A63B 60/00A63B 53/00A63B 2209/02A63B 60/0081A63B 53/10
45
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Claims

Abstract

Embodiments of the subject invention relate to a method and apparatus for providing a golf club shaft that has coupling between one or more bending modes and one or more twisting modes of deformation. In a specific embodiment, bending the shaft along a central longitudinal axis of the shaft in a plane of bending results in twisting of the shaft about the same central longitudinal axis of the shaft.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A golf club, comprising:
 a head; and   a shaft, wherein a first portion of the shaft comprises coupling between bending the first portion of the shaft along a first portion of the central longitudinal axis of the shaft in a first plane of bending and twisting the first portion of the shaft about the first portion of the central longitudinal axis of the shaft.   
     
     
         2 . The golf club according to  claim 1 , wherein the first portion of the shaft is the shaft such that the shaft comprises coupling between bending the shaft along the central longitudinal axis of the shaft in a plane of bending and twisting the shaft about the central longitudinal axis of the shaft. 
     
     
         3 . The golf club according to  claim 2 ,
 wherein the shaft comprises a proximal end and a distal end, wherein the head is connected to the distal end.   
     
     
         4 . The golf club according to  claim 3 , wherein the shaft comprises a shear center with respect to the proximal end being held fixed and a bending load being applied to the distal end, wherein the shear center is offset from the central longitudinal axis of the shaft in a direction perpendicular to the longitudinal axis. 
     
     
         5 . The golf club according to  claim 2 , wherein a cross-sectional shape of the shaft with respect to the central longitudinal axis of the shaft is circular. 
     
     
         6 . The golf club according to  claim 2 , wherein the shaft has a bending stiffness along the central longitudinal axis of the shaft that is constant for all planes. 
     
     
         7 . The golf club according to  claim 2 , wherein a clockwise torsional stiffness of the shaft about the central longitudinal axis of the shaft with respect to a clockwise torque applied at the distal end and the proximal end is equal to a counter-clockwise torsional stiffness of the shaft about the central longitudinal axis of the shaft with respect to a counter-clockwise torque applied at the distal end and the proximal end. 
     
     
         8 . The golf club according to  claim 2 , wherein a clockwise torsional stiffness of the shaft about the central longitudinal axis of the shaft with respect to a clockwise torque applied at the distal end and the proximal end is equal to a counter-clockwise torsional stiffness of the shaft about the central longitudinal axis of the shaft with respect to a counter-clockwise torque applied at the distal end and the proximal end for all elemental lengths of the shaft. 
     
     
         9 . The golf club according to  claim 2 , wherein the central longitudinal axis of the shaft is approximately a straight line when no bending forces are applied to the shaft. 
     
     
         10 . The golf club according to  claim 4 , wherein a center of mass of the head is offset from the central longitudinal axis of the shaft by a center of mass offset, wherein the center of mass offset is greater than zero. 
     
     
         11 . The golf club according to  claim 10 , wherein an offset-caused twist tends to occur when the club is rotationally accelerated about the proximal end in the plane of bending. 
     
     
         12 . The golf club according to  claim 10 , wherein the shear center is offset from the central longitudinal axis of the shaft by a distance in the range of 10% to 300% of the center of mass offset. 
     
     
         13 . The golf club according to  claim 12 , wherein the shear center is offset from the central longitudinal axis of the shaft in the same rotational direction with respect to the central longitudinal axis as the center of mass offset is offset from the central longitudinal axis of the shaft. 
     
     
         14 . The golf club according to  claim 12 , wherein the shear center is offset from the central longitudinal axis of the shaft in an opposite direction as the center of mass offset is offset from the central longitudinal axis of the shaft. 
     
     
         15 . The golf club according to  claim 12 , wherein the shear center is offset from the central longitudinal axis of the shaft at a shear center offset rotational angle with respect to the central longitudinal axis, wherein the center of mass is offset from the central longitudinal axis at a center of mass offset rotational angle with respect to the central longitudinal axis, wherein the shear center offset rotational angle is between 0° and 180° or between 180° and 360° away from the center of mass offset rotational angle 
     
     
         16 . The golf club according to  claim 12 , wherein the distance is in the range of 90% to 110% of the center of mass offset. 
     
     
         17 . The golf club according to  claim 12 , wherein the distance is in the range of 10% to 100% of the center of mass offset. 
     
     
         18 . The golf club according to  claim 12 , wherein the distance is in the range of 100% to 300% of the center of mass offset. 
     
     
         19 . The golf club according to  claim 2 , wherein there is approximately zero coupling between bending the shaft along the central longitudinal axis of the shaft in a second plane that is perpendicular to the plane of bending and twisting the shaft about the central longitudinal axis of the shaft. 
     
     
         20 . The golf club according to  claim 3 , wherein the shaft is tapered from a first cross-sectional area of the proximal end of the shaft to a second cross-sectional area at the distal end of the shaft, wherein the first cross-sectional area is greater than the second cross-sectional area. 
     
     
         21 . The golf club according to  claim 4 , wherein the shear center is offset from the central longitudinal axis of the shaft by a distance in a range of 0.1 inch to 8 inches. 
     
     
         22 . The golf club according to  claim 2 , wherein the shear center is offset from the central longitudinal axis of the shaft by a distance in a range of 0.1 radii of the distal end of the shaft and 30 radii of the distal end of the shaft. 
     
     
         23 . The golf club according to  claim 11 , wherein the coupling between bending the shaft and twisting the shaft causes a coupling twist in an opposite direction as the offset-caused-twist. 
     
     
         24 . The golf club according to  claim 11 , wherein the coupling between bending the shaft and twisting the shaft causes a coupling twist in a same direction as the offset-caused-twist. 
     
     
         25 . The golf club according to  claim 2 , wherein the coupling between bending the shaft and twisting the shaft extends a portion of the swing of a user where a face of the head is within 5 degrees of being square to the plane of bending when the user swings the club in the plane of bending. 
     
     
         26 . The golf club according to  claim 2 , wherein the coupling between bending the shaft and twisting the shaft at least partially compensates for a slice of a user swinging the golf club in the plane of bending. 
     
     
         27 . The golf club according to  claim 2 , wherein the coupling between bending the shaft and twisting the shaft at least partially compensates for a hook of a user swinging the golf club in the plane of bending. 
     
     
         28 . The golf club according to  claim 2 , wherein a torsional moment caused by an impact with an object by the head during a user swinging the golf club in the plane of bending is at least partially compensated for due to the coupling between bending the shaft along the central longitudinal axis of the shaft and twisting the shaft about the central longitudinal axis of the shaft. 
     
     
         29 . The golf club according to  claim 2 , wherein the shaft comprises a material having an anisotropic stiffness, wherein the material has a first axis of stiffness and a second axis of stiffness perpendicular to the first axis of stiffness,
 wherein a first stiffness along the first axis of stiffness is greater than a second stiffness along the second axis of stiffness,   wherein the first axis of stiffness is at an angle with respect to the central longitudinal axis greater than 0° and less than 90°, and   wherein the material contributes to the bend/twist coupling.   
     
     
         30 . The golf club according to  claim 29 , wherein the first stiffness is at least 2 times the second stiffness. 
     
     
         31 . The golf club according to  claim 29 , wherein the first stiffness is at least 10 times the second stiffness. 
     
     
         32 . The golf club according to  claim 29 , wherein the first stiffness is at least 100 times the second stiffness. 
     
     
         33 . The golf club according to  claim 2 , wherein there is at least 0.1° of twisting of the shaft for every 2% of a length of the shaft deflection of a distal end of the shaft with respect to a position of the central longitudinal axis before bending of the shaft. 
     
     
         34 . The golf club according to  claim 29 , wherein the material comprises carbon fibers. 
     
     
         35 . The golf club according to  claim 29 , wherein the material is positioned such that a first orientation of the first axis of the material of a first half of the shaft is a mirror image of a second orientation of the first axis of the material of a second half of the shaft,
 wherein the first half and second half are separated by a separation plane perpendicular to the plane of bending,   wherein the central longitudinal axis is in the separation plane,   wherein a first orientation of the second axis of the material in the first half of the shaft is a mirror image of a second orientation of the second axis of the material in the second half of the shaft.

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