Abstract:
A device designed for extending a golf club shaft. The device is a three-piece mechanism with a bottom piece bonded into the top end of a tubular golf club shaft, and a plurality of top piece sizes that are removably connected to the bottom piece and provide the adjustments in club length. A special golf grip having an accordion like plurality of rings can expand or contract in accordance with the amount of club length adjustment.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a device for adjusting the length of a golf shaft. In particular, the invention concerns extending the length of the shaft by utilizing the device at the gripping end of the club. 
     BACKGROUND OF THE INVENTION 
     One of the most important factors in golf club equipment is the club shaft. The shaft transfers the golfer&#39;s power to the club. It provides the length, the flex, the torque and the weight for the club, therein giving the swing plane and shot desired. 
     Golf club shafts are available in various types of materials and structures. Steel shafts are stronger, last longer, more durable and generally less expensive than graphite or carbon fiber shafts, and are usually made from carbon steel, although stainless steel is sometimes used. The steel shafts are available in stepped or rifle designs. The graphite shafts are more expensive and less durable, however, the lighter weight creates greater swing speed for more power. Also available are multi-material and titanium shafts. 
     When installing a shaft, the proper length must be accurately determined. The length is as important to a golf shaft as is the flex or torque. Most measurements of shaft length involve a determination of a particular player&#39;s height and distance of his hands to the floor. Shaft length will impact whereon the clubface the ball will be consistently struck, and often, an incorrect shaft length is the main cause of a golfer to alter his natural swing arc in order to make optimum impact. According to most research, if ball impact is but 1 inch off-centre this can equate to a 14% loss of carry distance, so it is vitally important that the length of the club be accurately fitted for each particular player. 
     If it is seen in the fitting process that a player needs to adjust his club, such as adding an inch or two to the length of the club, it would be highly desirable to lengthen his present club(s) rather buy and install new shafts. 
     Prior art shafts having adjustable lengths have been used for many years for a wide variety of applications. Each of these applications has its own functional and aesthetic requirements for the shaft construction which is employed. As a consequence, a number of different mechanisms and devices have been developed to satisfy the particular application requirements. A majority of golf club shaft extension patents are directed to use mainly as putters, or to extending shafts of an existing set of clubs to accommodate growing children. While the teachings of the present invention may be adopted to these type of applications, the focus is rather to make a club adjustment that is rigid, secure, and easily fastened. 
     SUMMARY OF THE INVENTION 
     The present invention provides for an extension device for use on the butt-end of a golf club shaft. The device consists of three basic parts: a top piece; a bottom piece; and an inner screw. The bottom piece is bonded, by glue or epoxy, into the tubular opening in the top of the club shaft. The top piece is attached to the bottom and provides for an extension in the club length. The invention can be used to extend any of the golf clubs in a set, but preferably is designed for use with a driver. Holding the device together in a tight unitary structure is an inner screw that traverses through the pieces. 
     In one embodiment of the invention the bottom piece has a plurality of resilient legs that are inserted and bonding into the upper end of the shaft. The top piece is attached in a removable sliding relationship to the bottom piece and by rotation of the inner screw, the device can extend and contract. The greatest variation in shaft length is basically achieved by having multiple top pieces that vary in length, however, minor adjustments in length can be achieved by rotation of the inner screw, therein causing the top piece to either expand or contract from the bottom piece. Once the device is installed it is covered by a grip. The invention requires the use of a special grip that has an opening in the butt-end for access of a tool wielded by the golfer, whereby by turning the inner screw the golfer can make small but important refinements in club length. The grip includes a series of pleated rings that can expand or contract like an accordion in response to changes in length of the device. 
     Another embodiment of the invention attaches the top piece into a bottom piece by essentially snapping the pieces together and then tightening the device with a screw traversing through the pieces. The varying extensions of the shaft being achieved by the selection of interchangeable top pieces of varying lengths. 
     Another embodiment of the invention forms the device by screwing the top piece into the bottom piece and tightening the device with an inner screw. 
     Other advantages of the invention will be more fully apparent from the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of two club shaft butt-ends, one illustrating the club when in the standard position and the other when the club shaft has been extended. 
         FIG. 2  is a pictorial view of the extension mechanism when in a complete state. 
         FIG. 3  is a symmetrical lengthwise view of the top piece of the butt extension. 
         FIG. 4  is a cross sectional view of  FIG. 3  with the turning screw installed. 
         FIG. 5  is a symmetrical view of the bottom piece of the butt extension. 
         FIG. 6  is a cross-sectional view of  FIG. 5  with the turning screw installed. 
         FIG. 7  is a cross-sectional view of the mechanism bonded to top of club shaft. 
         FIG. 8  is a symmetrical view of the shaft with length extended. 
         FIG. 9  is a cross-sectional view of the grip covering the mechanism. 
         FIG. 10  is a perspective view of another embodiment of the invention. 
         FIG. 11  is an expanded bottom perspective view of the embodiment of  FIG. 10 . 
         FIG. 12  is a perspective view of the upper portion of  FIG. 10 . 
         FIG. 13  is a top perspective view of the lower portion of  FIG. 10 . 
         FIG. 14  is a detailed prospective view of another embodiment of the invention. 
         FIG. 15  is an expanded view of the device shown in  FIG. 14 . 
         FIG. 16  is a perspective view of the upper portion of the device of  FIG. 14 . 
         FIG. 17  is a perspective view of the lower portion of the device of  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the comparison in the grip end between a standard club  100  and a club  102  that has been adjusted by the extension device of the present invention. The amount of the extension E is typically between 0.125 to 3 inches. 
       FIG. 2  is an illustration of the generic device  104  of the present invention. It is comprised of three basic pieces, a top piece  106 , a bottom piece  108 , and an inner screw  110  that holds the device securely together. 
       FIGS. 3 and 4  describe the top piece  106  of this invention which consists of a longitudinal cylindrical sidewall containing a plurality of slots  112  defined therein. The slots  112  are molded into the top piece  106  and preferably there are three. The upper end  114  of the top piece  106  contains an upper recess  126  for seating of the top end  118  of the inner screw  110 . The lower end  116  has a lower recess  124  defined therein and between the recesses  124 ,  126  is a clearance hole along the axis of the top piece  106  for free passage of the inner screw  110 . As seen in  FIG. 4 , these recesses  124 ,  126 , provide room to securely hold the inner screw  110  which has a conventional type of fitting and is capable of being turned by a conventional tool. The inner screw  110  contains first and second locking nuts  120 ,  122  essential to the operation of the device as described below. The bottom end of the screw  110 , although not shown in  FIG. 4  is threaded on the lower portion. 
       FIGS. 5-8  describe the bottom piece  108  which comprises a plurality of fingers  130  which extend upwardly and have distal ends  132 . The fingers are preferably three in number and are shaped and sized to coordinately slide into and within the slots  112  of the top piece  106 . The lower section of the bottom piece  108  has a plurality of resilient legs  134  which have distal ends  136  that are pressed with great bias into the open top end of the golf shaft, this is best shown on  FIGS. 7-9 . 
       FIGS. 6-9  show the second locking nut  122  of the inner screw  110  movably disposed in the chamber  138  of the bottom piece  108 , as it is free to traverse within the chamber  138  when actuated by the turning of the screw  110 .  FIGS. 7-8  illustrate the entire device  102  with the bottom piece  108  bonded, by glue or epoxy, to the inner wall of the golf club shaft  140 . In a standard position, shown in  FIG. 7 , the fingers  130  of the bottom piece  108  come to an abutment with the slots  112  of the top piece  106 . At that point any lengthening of the shaft is due entirely to the length of the device extending from the top of the shaft.  FIG. 8  is illustrative of what results when the device has been actuated by turning the screw  110  and the first and second locking nuts  120 ,  122  come into engagement with the top piece  106  therein lifting the top piece away from the bottom piece  108 . The amount of this extension tweaking can be indicated by the distance of the gaps  142  that appear in  FIG. 8 . The length of the adjustment is controlled by the second locking nut  122  coming to rest against the stop  128 . While not shown, the chamber  138  is threaded to allow a controlled, precise movement therein. The gaps  142  are not of a size that would be perceivable to the golfer through the grip  112 . 
       FIG. 9  is a cross-sectional view of the entire device  104  installed in the tubular shaft  140  with the grip  144  having pleated rings  146 . Since the device  104  may vary in length, it is necessary that the grip is capable of adjusting to various shaft lengths. The grip shown in  FIG. 9  has pleated rings that operate like an accordion when the grip stretches or contracts to accommodate the various extensions of the device. The grip  144  has a top opening for access of the tool to adjust the length or remove the top piece. 
     Another embodiment of the invention is shown on  FIGS. 10-13 , wherein a device  204  has basic three pieces, the top piece  206 , the bottom piece  208  and the inner screw  210 . This embodiment  204  presses the bottom piece  208  into the upper shaft  140  of the golf club and connects the top and bottom pieces by snap-fitting a plurality of teeth  212  located on the lower surface  216  of the top piece  206  into a like number of receptacles  222  defined in the upper surface  220  of the bottom piece  208 . The preferred number of teeth  212  and receptacles  222  being three. With this embodiment, varying the extension length is a direct function of the varying lengths of the top piece  206 . The device  204  is tightened by an inner screw  210  which is located at the upper surface  218  of the top piece  206  and traverses the top piece through a cylindrical opening  214  and then screws into a threaded section  224  of the bottom piece  208 . In actual operation, the user rotates the screw  210  by using a standard tool that fits in an opening at the top of the grip. To adjust the length the golfer removes the screw  210  and unsnaps the top piece  206  from the bottom piece  208  and replaces it with a top piece of another size length, either shorter or longer, therein causing the change to the overall the club length. 
     Another embodiment of the invention is shown in  FIGS. 14-17 , wherein the top piece  306  is screwed into the bottom piece  308  and the inner screw  310  tightens and secures the device  304 . The top piece  306  has a longitudinal cylindrical opening  318  that runs through the piece which has two major segments: a cylindrically shaped upper body  312  and a large threaded segment  314  for screwing into the bottom piece  308 . The bottom piece has a large threaded receptacle  316  in the top surface  322  of the bottom piece  308  for accepting the large threaded segment  314  of the top piece and a smaller threaded opening  320  for accepting the threaded bottom section of the inner screw  310 . To adjust the length of the shaft, the golfer removes the screw  310  and unscrews the top piece  306  from the bottom piece  308  and as above replaces it with a top piece of another length, either shorter or longer, therein creating the desired overall the club length. 
     Conformance with the rules of golf and acceptance by the USGA is an important consideration in this invention. As discussed above, the features of lengthening the club shaft must be such that it is virtually impossible to assemble and use in a manner which is not conforming. An aspect of this conformance is that any club with adjustable parts must have its parts firmly fixed with no reasonable likelihood of them working loose during a round of golf. The use of the inner screw and structure of the top and bottom pieces assures such protection. 
     It will be understood that various modifications to the preferred embodiment disclosed above may be made. The above description is not intended to limit the meaning of the words used in the following claims that define the invention. Rather, it is contemplated that future modifications in structure, function or result will exist that are not substantial changes and that all such insubstantial changes are intended to be covered by the following claims.