Abstract:
A golf club includes a tubular shaft, a golf club head affixed to a first end of the tubular shaft, and a grip abutting a second end of the shaft. The golf club further includes an adjustable counterbalance that is insertable within a hollow recess of the grip. The adjustable counter balance includes an elongate member adapted to be secured to the tubular shaft, and a movable weight. The movable weight is selectively transitionable between a first, unlocked state that permits translation of the weight along the elongate member, and a second locked state that restrains the weight from free translation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of and claims the benefit of priority from U.S. application Ser. No. 14/628,846, filed Feb. 23, 2015, which is a continuation-in-part of and claims the benefit of priority from U.S. application Ser. No. 14/493,397, filed Sep. 23, 2014, both of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to a golf putter having an adjustable counterbalance weight. 
       BACKGROUND 
       [0003]    Putting is one of the most precise aspects of the game of golf. It requires a considerable amount of consistency to properly align and strike a ball so that it rolls on an intended line for a desired distance. To facilitate a consistent stroke, many golfers look favorably on a putter that provides smooth stroke, good glide, pure impact, and a bounce-less topspin ball launch. 
         [0004]    One strategy to remove uncertainty in a putting stroke has been to anchor an extended length putter into the midsection of the golfer. Doing so reduces the total number of degrees of freedom that must be successfully controlled to provide a smooth, substantially planar stroke. Such a practice has been prohibited by rules established by the USGA and R&amp;A rule making bodies. As such, club manufacturers have taken on a renewed interest in the design of the putter to fill the void left by the prohibition on anchored-style putters. 
       SUMMARY 
       [0005]    In one embodiment, a golf club includes a tubular shaft, a golf club head affixed to a first end of the tubular shaft, and a grip abutting a second end of the shaft. The golf club further includes an adjustable counterbalance that is insertable within a hollow recess of the grip. The adjustable counter balance includes an elongate member adapted to be secured to the tubular shaft, and a movable weight. The movable weight is selectively transitionable between a first, unlocked state that permits translation of the weight along the elongate member, and a second locked state that restrains the weight from free translation. 
         [0006]    In another embodiment a golf club includes a tubular shaft that extends between a first end. The tubular shaft has an inner surface that defines a hollow recess and has a length of from about 35 inches to about 38 inches. A putter head is affixed to the first end of the tubular shaft, where the head has a loft angle of from about 0 degrees to about 6 degrees and a mass of from about 360 grams to about 390 grams. A movable weight is disposed within the hollow recess and is selectively repositionable throughout a translatable range of from about 250 mm to about 400 mm, where the translatable range extends from the second end of the tubular shaft toward the first end. Furthermore, the movable weight has a mass of from about 60 grams to about 80 grams, which together with the heavier than normal head, provides a smooth putter stroke that simulates that of an anchored putter. 
         [0007]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic side view of a golf club, such as a putter. 
           [0009]      FIG. 2  is a schematic partial cross-sectional side view of a putter having an adjustable counterbalance disposed within a hollow recess of a shaft of a golf club. 
           [0010]      FIG. 3  is a schematic cross-sectional side vice of an embodiment of an annular weight portion of an adjustable counterbalance for a golf club. 
           [0011]      FIG. 4  is a schematic cross-sectional side vice of an embodiment of an annular weight portion of an adjustable counterbalance for a golf club. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring to the drawings, wherein like reference numerals are used to identify like or identical components in the various views,  FIG. 1  schematically illustrates a golf club  10  that includes a shaft  12 , a golf club head  14 , and a grip  16 . The shaft  12  is generally disposed along a longitudinal axis  18  and extends between a first end  20  and a second end  22 . The golf club head  14  is affixed to the first end  20  of the shaft  12 , and the grip  16  is circumferentially disposed about the outside of the shaft  12  such that the grip  16  abuts the second end  22 . The total length of the golf club  10  may be from about 30 inches to about 50 inches, or from about 34 inches to about 40 inches, or even from about 35 inches to about 38 inches. In general, the grip  16  may be a non-metallic wrap or sleeve that is gripped by a user when swinging the club. Suitable materials for the grip typically include a rubber, leather, or synthetic leather material. The grip  16  may have a length of, for example, about 15 inches, extending from the second end  22  of the shaft  12 . In one configuration, the golf club head  14  is a putter head that has a loft angle of from about 0 degrees to about 6 degrees, and a head mass of from about 300 g to about 500. In other embodiments, the club head  14  may have a head mass of from about 325 g to about 425 g, or from about 360 g to about 400 g, or from about 360 g to about 390 g, or even from about 365 g to about 375 g. In one particular example, the head mass may be about 368 g to about 372 g. Such a design may be viewed as having a heavier head than typical or traditional putters, but it has been found that the heavier head may provide a smoother stroke and additional control, particularly on fast greens. 
         [0013]      FIG. 2  schematically illustrates a partial cross-sectional view  30  of the shaft  12  of  FIG. 1 . As shown, the shaft  12  includes a tubular body  32  having an inner surface  34  and an outer surface  36  that are substantially concentric and aligned with the longitudinal axis  18 . The grip  16  is disposed about the outer surface  36 , and the inner surface  34  defines a hollow recess  38 . An adjustable counterbalance  40  may be disposed within the hollow recess  38 , and may enable a movable weight  42  to be selectively repositioned by a user at an intended location within the shaft  12 . By repositioning the movable weight  42  within the shaft  12 , the user may alter the feel and response of the club  10  when it is swung. For certain placements and sizes of the movable weight  42 , the feel or swing profile of the club  10  may be similar to that of an anchored putter. While the anchored putter feel is highly golfer-specific, it has been found that the combination of longer shaft lengths (e.g., about 35 inches to about 38 inches) and heavier putter heads (e.g., about 360 g to about 400 g, or more preferably about 360 g to about 390 g) suitably mimic the anchored feel when combined with the movable weight  42  described herein. 
         [0014]    As shown in  FIG. 2 , the adjustable counterbalance  40  includes an elongate member  44  that is configured to be substantially aligned with the longitudinal axis  18  of the shaft  12 . The elongate member  44  may include a rod formed from a suitably light weight, yet resilient material, such as, for example, an aluminum, a carbon fiber-wrapped aluminum, and/or a polymeric material. Examples of suitable polymers may include one or more polyamides, polyimides, polyamide-imides, polyetheretherketones (PEEK), polycarbonates, engineering polyurethanes, and/or other similar materials. In general, the polymeric material may be a either thermoplastic or thermoset, and may be unfilled, filled with a chopped fiber such as a glass fiber or a carbon fiber, or may have other suitable fillers and/or additives to promote increased strength. The rod may have a diameter that is from about 10% to about 25% of the diameter of the hollow recess  38 . Likewise, the rod may have a length of from about 300 mm to about 450 mm, or from about 350 mm to about 400 mm. In one particular example, the rod may have a length of about 15 inches or about 380 mm. 
         [0015]    In one configuration, the movable weight  42  may be generally annular in nature and may radially surround the elongate member  44 . The weight  42  may be selectively affixed to the elongate member  44  to facilitate a semi-permanent placement of the weight  42 . For example, the weight  42  may be transitionable between a first, unlocked state and a second, locked state at the urging of the user. When configured in a first, unlocked state, the annular weight  42  may be translatable throughout a translatable range (e.g., between a first end  46  and a second end  48  of the elongate member  44 ). Once the annular weight  42  is suitably positioned by a user, the weight  42  may be transitioned into a second, locked state, where it is then restrained from further translation. 
         [0016]      FIG. 3  schematically illustrates a partial cross-sectional view  60  of an embodiment of an annular weight  42  that is configured to be selectively translatable along the elongate member  44 . As shown, the annular weight  42  may include a first section  62  and a second section  64  that each circumferentially surround the elongate member  44  and are adjacent to each other along the length of the member  44 . 
         [0017]    In one embodiment, the annular weight  42  shown in  FIG. 3  may selectively transition between the first, locked state and the second, unlocked state by rotating the first section  62  relative to the second section  64  about the elongate member  44 . In one configuration, the transition may be completed through a relative rotation of from about 45 degrees to about 180 degrees. In another configuration, the transition may be completed through a relative rotation of from about 80 degrees to about 130 degrees, or approximately from about a quarter of a full rotation to about a third of a full rotation. In one embodiment, this relative rotation may draw the respective sections  62 ,  64  toward each other to apply an axially compressive force to a grommet  68  located between the two sections  62 ,  64 . The applied compressive force causes the grommet  68  to radially expand against the elongate member  44  with a sufficient contact force to inhibit the annular weight  42  from freely translating along the elongate member  44  (i.e., selectively affixing the annular weight  42  to the elongate member  44 ). The grommet  68  may be formed from a polymeric material and may have a hardness, measured on the Shore A scale, of from about 40 A to about 90 A, though more preferably from about 70 A to about 90 A. 
         [0018]    The desired holding force between the movable weight  42  and the elongate member  44  is preferably greater than about 8 lbf when in a locked configuration. In one configuration, the locked configuration may be characterized by a holding force of from about 8 lbf to about 20 lbf, or even from about 8 lbf to about 15 lbf. These ranges are intended to approximate the impact loading of the club being dropped or being aggressively placed into a golf bag. Conversely, while in the unlocked state, the holding force is preferably less than about 1 lbf, or even more preferably less than about 0.5 lbf. To accomplish the desired locked-holding force without requiring an excessively large locking torque (i.e., a torque larger than an average person can provide without a tool), particular attention must be given to the physical and material design of the grommet  68 . 
         [0019]    In general, the grommet  68  should be dimensioned to be in a close arrangement with a stationary locking surface when the weight  42  is in an unlocked state, and should be dimensioned to make forcible contact with the locking surface when in an unlocked state. In the embodiment shown in  FIG. 3 , the locking surface would be the OD of the elongate member  44 . Therefore, the ID of the grommet  68 , when in a relaxed state, should be designed/dimensioned to have a maximum clearance relative to the elongate member  44  of up to about 0.1 mm, or up to about 3% of the radial thickness of the grommet  68 . In a more preferable configuration, the grommet  68  the ID of the grommet  68  is designed/dimensioned to have a slight interference fit against the locking surface. This interference may be up to about 0.15 mm, or up to about 5% of the radial thickness of the grommet  68 . 
         [0020]    It has been found that, in the present design, grommets formed from certain polymers can take a compression set that causes the grommet  68  to lose holding power. This durability issue has been overcome by forming the grommet from a material that is sufficiently resistant to taking a compression set, though still sufficiently soft to enable locking by hand. These properties have been obtained by annealing an otherwise suitable thermoplastic polyurethane grommet to improve the compression set resistance and long-term holding power. A suitable annealing process may involve maintaining the grommet in a 70 degree Celsius environment for 22 hours. 
         [0021]    As noted above, the maximum torque required to secure the weight  42  in place should be low enough to perform by hand (preferably without the need for a tool). For example, in one configuration, the maximum required torque that is needed to lock the weight  42  in-place should be less than about 7.0 inch-pounds. To aid in the manual rotation, in one configuration, the outer surface of a portion of each section  62 ,  64  may be knurled or otherwise textured. 
         [0022]    In one particular design, such as shown in  FIG. 3 , the first section  62  may define a recess  70  that is configured to receive, and radially surround a portion  72  of the second section  64 . An annular grommet  68  may be disposed within the recess  70  such that it is radially positioned between the elongate member  44  and a portion of the first section  62 . The nested portion  72  of the second section  64  may be drawn into or out of the recess  70  at the urging of a locking interface  74 . 
         [0023]    The locking interface  74  may include, for example, threaded portions of the first and second sections  62 ,  64  that cooperate to cause a relative translation of the sections  62 ,  64 . In another embodiment, such as shown in  FIG. 3 , the locking interface  74  may include a protrusion  76  and a ramped slot  78  or track, similar to a BNC-style coaxial wire connector. The protrusion may extend in a radial direction from one of the first and second sections  62 ,  64 , and the slot  78  or track may be defined by the other. The slot  78  may extend around a portion of the circumference of the annular weight  42 , and may include a length  80  that is ramped in an axial direction. The protrusion  76  may be captured within the slot  78 , and a relative rotation of the first and second sections  62 ,  64  would result in a relative translation of the sections  62 ,  64  (particularly as the protrusion  76  moves through the ramped length  80  of the slot  78 ). In one embodiment, the slot  78  may be provided in the first section  62 , and the protrusion  76  may extend radially outward from the nested portion  72  of the second section  64 . 
         [0024]    In another design, the annular weight  42  may include two or more annular grommets  68  that are operative to selectively restrain translation of the weight  42  along the elongate member  44 . For example, as shown in  FIG. 4 , the annular weight may include a first annular grommet  82  disposed between the first section  62  and a weight tube  84 , and may include a second annular grommet  86  disposed between the second section  64  and the weight tube  84 . The first and second sections  62 ,  64  may meet at a similar locking interface  74  as described above, though transitioning from an unlocked state to a locked state may involve compressing each of the first and second grommets  82 ,  86  against the weight tube  84 . The compressive force may cause the first annular grommet  82  to expand between the elongate member  44  and the first section  62  and may cause the second annular grommet  86  to expand between the elongate member  44  and the second section  64 . In still further designs, the weight tube  84  may be subdivided with additional annular grommets disposed at intermediate locations between sections of the weight tube. 
         [0025]    Referring again to  FIG. 2 , the adjustable counterbalance  40  is configured to be selectively secured to the second end  18  of the shaft  12 . In one configuration, the adjustable counterbalance  40  includes a securing means coupled with the elongate member  44  at, or proximate to, the first end  46  of the member  44 . The securing means may be configured to selectively couple the adjustable counterbalance  40  to the second end  18  of the shaft  12 . In one configuration, the securing means is an externally threaded cap  90  that is affixed to the first end  46  of the elongate member  44 . The externally threaded cap  90  is configured to cooperate with a threaded portion of the inner surface  34  of the shaft  12  to secure the cap  90  within the hollow recess  38 . In other configurations, the securing means may be a press-fit style connection, or may include an internally threaded, lid-style cap that may screw onto a portion of the end of the shaft  12 . 
         [0026]    A stabilizing grommet  92  may be disposed on the second end  48  of the elongate member  44 , and may be used to stabilize the elongate member  44  within the hollow recess  38 . This stabilizing grommet  92  has an external diameter that is dimensioned so that when the grommet  92  is inserted within the tubular body of the golf club shaft, it may apply a contact force against the inner surface  34  of the shaft  12 . Additionally, one or more stabilizing grommets  92  may be disposed on the annular weight  42  for a similar, stabilizing purpose. For example, as shown in  FIG. 2 , in one configuration, a first stabilizing grommet  94  may be disposed around the first section  62  and a second stabilizing grommet  96  may be disposed around the second section  64 . Each stabilizing grommet  94 ,  96  may be compressed between the respective section  62 ,  64  and the inner surface  34  of the shaft when the adjustable counterbalance  30  is inserted within the hollow recess  38 . 
         [0027]    In one configuration, an adjustable counterbalance  30  for a putter, may enable a mass of from about 30 g to about 100 g to be movable within a hollow recess  38  of the shaft  12  throughout a translatable range of from about 200 mm to about 500 mm. Said another way, in this embodiment, the movable weight  42  may have a mass (i.e. a “movable mass”) of from about 30 g to about 100 g, where the center of mass for the movable weight  42  is translatable along the elongate member  44  (and securable thereto) throughout a range of from about 200 mm to about 500 mm. In other configurations, the adjustable counterbalance  30  may enable a mass of from about 60 g to about 80 g to be movable within the hollow recess  38  throughout a range of from about 250 mm to about 400 mm. In one particular example, the adjustable counterbalance  30  may enable a mass of about 65 g to about 75 g to be movable within the hollow recess  38  throughout a range of about 250 to about 350 mm. In one configuration, the translatable range may extend from the second end  22  of the shaft  12  toward the first end  20 . In this manner, all or most of the translatable range may be coincident with the grip  16 . These movable mass and translation ranges have been found to provide the ideal amount of counterbalancing and adjustability to provide certain stabilizing effects found with an anchored putter. 
         [0028]    The entire mass of the adjustable counterbalance  40  may be from about 50 g to about 120 g, which includes from about 30 g to about 100 g of movable mass, and about 20 g of fixed mass (i.e., mass of the elongate member  44  and other stationary components). In one configuration, the grip  16  may define a “grip portion” of the club. More specifically, the grip portion includes the entire portion of the golf club that is coincident with the grip  16 . As noted above, the movable weight  42  may be selectively repositionable within the grip portion to provide the feel of an anchored putter. The grip portion may have a total fixed mass (i.e., the mass of the non-repositionable elements) that is from about 60 g to about 120 g. In another embodiment, the total fixed mass of the grip portion is from about 80 g to about 100. In one particular embodiment, the total fixed mass of the grip portion may be about 90 g. 
         [0029]    To provide the most optimal feel and adjustability to a golfer, the amount of the movable mass may fall within certain proportions, such as expressed by the ratio of movable mass to head mass and/or to the fixed mass within the grip portion. In one configuration, the ratio of the head mass to the movable mass may be from about 3:1 to about 11:1, or from about 3:1 to about 8:1, or even from about 4:1 to about 6:1. In a particular example, the ratio of the head mass to the movable mass may be about 4.5:1 to about 5.5:1, which may provide a suitable amount of swingweight/inertia on the clubhead to provide a desirably smooth stroke while still affording sufficient counterbalancing adjustability. Likewise, the ratio of the fixed grip mass to the movable mass may be from about 0.5:1 to about 4:1, or from about 0.5:1 to about 2:1, or even from about 0.75:1 to about 2.0:1. In a particular example, the ratio of the fixed grip mass to the movable mass may be about 1.2:1, which may provide a suitable ability to re-locate the center of mass of the heavier-than-normal grip portion. 
         [0030]    In one configuration, the elongate member  44  may be color coded, or may have other suitable visual markings, that may allow a user to quickly identify specific regions or weight configurations that may be desirable. For example, in one embodiment, there may be at least three colored regions along the length of the elongate member  44 . These may correspond to high, mid, and low weight configurations. 
         [0031]    While various embodiments have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims. 
         [0032]    “A,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that at least one of the item is present; a plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; about or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range. Each value within a range and the endpoints of a range are hereby all disclosed as separate embodiment. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated items, but do not preclude the presence of other items. As used in this specification, the term “or” includes any and all combinations of one or more of the listed items. When the terms first, second, third, etc. are used to differentiate various items from each other, these designations are merely for convenience and do not limit the items.