Patent Publication Number: US-8529365-B1

Title: Indoor golf swing practice implement

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to technique practice implements for golf and is distinguished from exercise devices utilizing weight resistance for weight training, strength training or muscle conditioning. 
     The balance, felt heft and swinging weight of golf clubs have been measured and compared since around the year 1934 by measuring the moment (torque, or moment of force) of the golf club produced by the weight of the golf club acting at its center of gravity about an axis (or fulcrum) that is a predetermined distance from the butt end (proximal end) of the golf club. This moment has been known since about 1934 as the swinging weight, swingweight moment or simply the swingweight of the club. The most widely used predetermined distance from the butt of the club is 14 inches, but any other distance could be used; and 12 inches was proposed around the year 1948 but has not gained widespread favor in the golf club industry. The swingweight moment is directly expressed in terms like inch-grams. The golf club industry widely uses the “Lorythmic” swingweight scale to translate these inch-gram measurements into a letter and number scale like D2 which is equal to a 14 inch fulcrum swingweight moment of 6150 inch-grams. Each numerical step equals a 50 gram change in the swingweight moment. Swingweight moment is distinguished from moment of inertia which is very sensitive to the length of the golf club and is expressed in terms like gram-inches squared (gram-inches squared). 
     There are few, if any, neutrally weighted full length golf training aides, that is to say few that are not overly heavy and not substantially eccentrically off balanced relative to a conventional club. If a user desires a full size implement for practicing the golf swing that is weighted like and, when swung in the manner of a golf club, feels like a conventional golf club, the user is likely to choose a conventional golf club, with which the user can either practice his swing or hit balls on a driving range. Most golf swing training devices are consistently relatively heavy compared to a conventional golf club because their objective is muscle strengthening or muscle training. There is no shortened golf swing practice implement available that is weighted and balanced to feel like a conventional golf club and yet is substantially smaller than conventional golf clubs. 
     The prior art devices are typically either 1) heavier than a regular golf club for weight training, muscle training or muscle building, or 2) axially offset to exaggerate the release of the wrists in the swing. The devices disclosed by Matthews (U.S. Pat. No. 1,524,196) are both shortened and stated to be intended to feel like a regular golf club. However, the Matthews device is based on the calculation of the moment of the implement around the fixed point of the left shoulder of a golfer. This use of moment calculation of golf implements is inadequate to determine the “heft” or “swinging weight” of the implement which is believed to be a better determinant of the perceived feel of a club. 
     In 1934, Robert Adams patented the first “Apparatus for Measuring the Moments of Golf Clubs and the Like” (Adams, U.S. Pat. No. 1,953,916). Adams disclosed that the “heft” or “swinging weight” of a golf club could be measured and compared by determining the moment of the golf club “about a point a fixed distance from one end of the implement”; and then “found in actual practice that satisfactory results are realized if the fixed point is fourteen inches from the grip end.” 
     The Adams swingweight moment calculation is sensitive to changes in the center of gravity in the club itself. The Matthews&#39; moment calculation is relatively insensitive to changes in the center of gravity in the club itself. The relatively long moment arms in the Matthews device reduce the importance of the balance, mass distribuition and feel of the practice implement itself. As a result, the Matthews moment calculation is not effective for determining how the exercise implement will “feel” when swung by a golfer. The resulting device “feels” like a regular golf club only if the wrists are not cocked in the backswing or uncocked in the downswing. The required stiff armed swing is not a golf swing. When swung like a regular golf club, with a regular golf swing, including the cocking of the wrists in the backswing, the uncocking of the wrists in the downswing, and the refolding of the wrists in the followthrough, the Matthews device would feel extremely light; its “heft” or “swinging weight” are not at all similar to a regular golf club. It offers too little of the swingweight moment of a regular length golf club around the center of motion of the hands and wrists. The center of gravity of the Matthews device is very near the end weight, and therefore not balanced like a regular golf club. 
     Neither the techniques used by Matthews and Adams are useful for very short clubs. For example, the Adams 14 inch fulcrum point swingweight scale cannot be used to measure the “heft” or “swinging weight” of very short practice implements when the total length of the device is shorter than the 14 inch fulcrum point or when the center of gravity of the device is at, near or inside the 14 inch fulcrum point. 
     Examination of other prior art devices does not reveal a training device that is both substantially shorter than conventional golf clubs and yet retains the feel of a conventional club when used in typical golf swings. What is needed is a training device that can be swung in the exact manner of golf motions while the user is in limited space and that at the same time provides the user with the same feel of a conventional golf club. 
     SUMMARY OF THE INVENTION 
     The current invention is an indoor golf swing practice implement that is weighted and balanced to feel like a regular golf club but having a very short length which can be used indoors in very small spaces such as are found in nearly all homes, apartments or offices. 
     The inventive device is distinguished from prior art by the smaller size and neutral weighting of the inventive device. The weighting is neutral both in terms of user-perceived heft, balance, swinging weight and in regard to weight offset from the axis of the shaft of the device. In view of the foregoing, it is the object of this invention to produce an indoor golf swing practice implement of simple construction which feels like a conventional golf club but is approximately 18 inches in total length and therefore useable indoors in very small spaces. 
     The current invention balances the weight of the shaft and an end weight in such a way as to place the center of gravity of the device in the proportionally similar position to a conventional golf club of longer length resulting in the feel of an actual conventional golf club when swung by a skilled golfer. 
     The inventor has found that using a fulcrum point four inches from the butt of the very short practice implement produces satisfactory and useful comparative “heft” and “swinging weight” moment calculation for very short practice implements. In preferred embodiments, the current invention includes an elongated shaft with a concentrated weight secured to one end. Adjacent the other end, the shaft has a grip similar to a standard golf grip. The combined moments of the components of the implement, about a point four inches from the proximal or butt end of the implement, is in the range of 9,500 to 11,000 inch grams. At the same time, the center of gravity of the implement is located at a distance from the distal end of the club equal to 20 to 25 percent of the total length of the implement. These parameters have been found to satisfy the objective of the invention in a novel way. 
     The inventive implement provides a unique structure and method of personal golf practice and training unavailable in prior devices. Additional aspects and advantages of the inventive implement are made clear in the following discussion of exemplary embodiments and the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of an inventive practice implement standing vertically on the cylindrical weight. 
         FIG. 2  is an isometric view of two parts of an inventive practice implement. 
         FIG. 3  is an isometric view of an alternative embodiment of the inventive practice implement with an indicium on the cylindrical weight. 
         FIG. 4  is an isometric view of the cylindrical weight in the alternative embodiment including indicia on the side and distal end of the cylindrical weight. 
         FIG. 5  is an elevation view of an alternative embodiment of the practice implement with a conventional golf club head added below the cylindrical weight. 
         FIG. 6  is an elevation view of an inventive practice implement showing the location of a four inch swinging weight fulcrum point. 
         FIG. 7  is an elevation view of a conventional golf club (Prior Art) showing the location of the four inch swinging weight fulcrum point. 
         FIG. 8  is an elevation view of an alternative embodiment of the inventive practice implement with a simulated golf club head attached to the shaft. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     List of Reference Numerals 
     
         
         
           
               12  shaft 
               12   a  conventional club shaft 
               14  cylindrical end weight 
               16  grip 
               18  center of gravity 
               18   a  center of gravity of a conventional golf club 
               22  proximal end of the cylindrical end weight 
               24  distal end of the cylindrical end weight 
               26  proximal end of the shaft 
               28  distal end of the shaft 
               30  male threads 
               32  female threads 
               34  four inch swinging weight fulcrum point 
               34   a  four inch swinging weight fulcrum point on conventional club 
               38  simulated golf club head 
               38   a  conventional club head 
               39  heavy simulated golf club head 
               40  indicium on side of cylindrical weight 
               42  indicium on distal end of cylindrical weight 
               52  overall length of practice implement 
               52   a  overall length of conventional golf club 
               54  distance from distal end of practice implement to center of gravity 
               54   a  distance from distal end of conventional golf club to center of gravity 
           
         
       
    
     The first embodiment of the practice implement is illustrated as  FIG. 1  having a shaft  12 , a cylindrical end weight  14  and a grip  16  for holding the practice implement by a user. The shaft  12  in a preferred embodiment is made of solid aluminum, but may be made of thick walled steel tube or solid steel. The cylindrical end weight  14  is made from solid steel, but may be made from any similarly heavy metal or other material. The grip  16  in the embodiment shown is a standard prior art golf grip, but may be a training grip. 
     With reference to  FIG. 2 , the distal end of the shaft  28  preferably has male threads  30  which are threaded into the female threads  32  in the proximal end of the cylindrical end weight  22 . The shaft  12  is tightened into a normally fixed position in the cylindrical end weight  14 . The shaft  12  may be secured in the cylindrical end weight  14  by means of epoxy or other liquid applied gluing agent. 
     The distal end of the cylindrical end weight  14  preferably has a flat surface on which the practice implement can stand when stored on a flat surface. 
     With reference to  FIGS. 1 and 6 , the center of gravity  18  of the practice implement is located in the shaft  12  at a predetermined center distance dimension  54  from the distal end of the implement. The center distance dimension  54  is in the range of 20 to 25 percent of the total length dimension  52  of the implement. In this manner, is the positioning of the center of gravity  18  is configured to be substantially similar to the center of gravity of a typical conventional golf club (See  FIG. 7 ).  FIG. 7  illustrates the location of the respective center of gravity  18   a  in the shaft of a conventional golf club: a respective center distance dimension  52   a  in the range of 20 to 25 percent of the total length  54   a  of the conventional golf club. 
     The inventive practice implement has a moment of between 9,500 and 11,000 inch grams resulting from the total mass of the practice implement at its center of gravity  18  acting around a four inch (from the proximal end of the implement) swing weighting fulcrum point  34  as shown in  FIG. 6 . Moments referenced herein are defined as and calculated about an imaginary transverse axis through the fulcrum point  34 . No actual physical fulcrum is an element of the present inventive implement. Herein the term “moment” refers to the product of an object&#39;s mass and the object&#39;s effective lever arm distance perpendicular from the respective fulcrum. 
     The above 9,500 to 11,000 inch gram moment is substantially similar to the respective moment of a conventional golf club resulting from the total mass of the golf club at its center of gravity  18   a  acting around its respective four inch swing weighting fulcrum point  34   a  as shown in  FIG. 7 . 
     Experimentation has shown that an implement of only twelve inches in length is not long enough to create the feel of a regular golf club. Experimentation has shown that a length of approximately 18 inches is required to recreate the feel of a regular golf club. The total length dimension  52  of the embodiment of the practice implement shown in  FIG. 1  is preferably 18 inches, but a length of from 16 to 20 inches will be satisfactory. The shaft  12  may be coated or painted to protect the metal surface or to create a desired aesthetic appearance. The cylindrical end weight  14  is suggested to have a mass in the range of 500 to 1000 grams to achieve the desired balance and moment and should be formed of steel or material of closely similar density to ensure small size. 
     When swung by a skilled golfer, the practice implement shown in  FIG. 1  has a perceived heft and swinging weight that are substantially similar to that of a conventional golf club; but is short enough to be used indoors in very small spaces, such as are found in most single family homes, apartments and offices. 
     The conventional method in the prior art of determining the heft and swinging weight of golf clubs involves the calculation of the moment from the total mass of the golf club at its center of gravity acting around the fulcrum point 14 inches from the club proximal end. This does not work for very short practice implements. Very short practice implements, such as desired in the invention, have a center of gravity that is too near this associated fulcrum point for useful calculations. 
     The inventor&#39;s experiments and investigation have determined that the four inch swing weighting fulcrum point  34  as shown in  FIG. 6  will provide useful determinations of perceived heft and swinging weight for both very short practice implements and conventional golf clubs and will allow the comparisons of perceived heft and swinging weight. The four inch swinging weight fulcrum point  34  also eliminates the distorting impact of grip weight on swinging weight calculations. Experiments and investigations have determined that a moment of between 9,500 and 11,000 inch gram around the four inch swinging weight fulcrum point  34  will reproduce the felt heft and swinging weight of a conventional golf club. Using industry standard nomenclature, moments in the lower end of the above specified range will feel like lighter C6 to D0 swinging weight golf clubs. Moments in the high end of the range will feel like heavier D5 or D7 swinging weight golf clubs. Moments in the middle of the range will feel like standard D2 swinging weight golf clubs. Stronger men, or professional golfers may prefer a heavier weighting. Women and junior golfers may prefer a lighter weighting. In combination, the said moment of the practice implement and the balance of the practice implement created by the location of the center of gravity  18  of the practice implement produce when the practice implement is swung by a skilled golfer the feel of a conventional golf club. 
     A skilled golfer can grasp the inventive practice implement shown in  FIG. 1  as he would a conventional golf club. The practice implement can then be swung in the same manner as a conventional golf club. The skilled golfer can use the device to practice swinging indoors in very small spaces. The skilled golfer can use the device to check positions of the hands, shaft and head in various positions in the full swing. The device is particularly useful for checking the cardinal positions in the backswing and the stages of wrist cocking. For instance, a skilled golfer can check the position of the shaft and head as the arms, hands and shaft reach horizontal. Of special concern for the skilled golfer is whether the head of the club when these positions are reached is in front of or behind the hands. Practice in front of a mirror can be used to augment the golfer&#39;s perceptions of swing positions. A wide variety of similar types of positions and relationships can be checked, adjusted and confirmed throughout the entire golf swing; and then repetitively practiced. The neutral weighting of the practice implement will allow golfers to practice full swings with full release of the wrists through impact. 
     The neutral weighting of the practice implement also allows the golfer to practice the smaller swings in the game that do not involve a full release. These smaller chipping swings are widely understood to involve a less aggressive cocking of the wrist in the backswing and then a holding of the wrist cock through the impact area. The neutral weighting of the inventive practice implement does not introduce overweighted momentum. Many prior art practice devices are very heavy or have a heavy weight offset from the axis of the shaft to induce unnatural momentum into the practice swinging. This unnatural momentum is undesirable in the present invention. Heavy weights do not produce the “soft hands” required for a good short game. 
     The indoor golf swing practice implement shown in  FIG. 1  can be used all year long indoors in a variety of settings. The golfer in northern climates can use the device in the winter when access to golf courses is limited or impossible. The golfer can use the device all winter long to stay in golf condition with a well grooved swing instead of starting golf in the spring with a poorly grooved swing and in poor golfing condition. The working man or woman with little or no time during the work day for golf can find time to practice indoors at the end of the day in their home. 
     As shown in  FIGS. 3 and 4 , the addition of an indicium  40  on the side of the cylinder  14  will allow the golfer to more easily see the position of the club head during his practice. The addition of an indicium  42  on the distal end of the cylinder will allow the golfer to see the club head position when practicing in front of a mirror. These indicia can either be cut into the cylinder as a groove or painted or printed on the cylinder or adhered to the cylinder. 
     An alternative embodiment shown in  FIG. 5  includes the addition of a simulated conventional golf club head  38  below the cylindrical weight  14 . The addition of the significant weight of the simulated golf club head  38  will require that the weight of the cylindrical weight  14  be reduced correspondingly to maintain the desired moment around the four inch swinging weight fulcrum point  34  and the desired location of the center of gravity as discussed above. The simulated golf club head  38  in this alternative embodiment functions in the same manner as the indicia shown in  FIGS. 3 and 4 . 
     An alternative embodiment shown in  FIG. 8  includes a heavy simulated golf club head  39  attached to the shaft  12 . The heavy simulated golf club head is significantly heavier than a standard golf club head in order to create in the practice implement a moment of between 9,500 and 11,000 inch grams resulting from the total mass of the practice implement at its center of gravity  18  acting around the four inch swing weighting fulcrum point  34  as shown in  FIG. 8 . This 9,500 to 11,000 inch gram moment is substantially similar to the corresponding moment of a conventional golf club as discussed above. 
     From the description above, a number of advantages of some embodiments of my practice implement become evident: 
     (a) The current invention reproduces the feel of full sized conventional golf is a very short practice implement which can be used indoors in very small spaces; 
     (b) The current invention is neutrally weighted with respect to both the feel of the total weighting and the eccentricity of the total weighting in relation to the shaft of the implement. The current invention will not induce in the hands of a golfer using the implement an exaggerated release or excessive momentum due to overweighting for muscle building or training. 
     (c) The current invention can be used all year long indoors by golfers in northern climates with limited access to outdoor golf facilities for many months of each year. The current invention can be used indoors in the kinds of very small spaces that are found in most single family homes, apartment or offices. This will allow skilled golfers to maintain their golf swings and golf fitness through the winter. 
     (d) The current invention can be stored standing vertically on its flat distal end. This very compact storage posture will allow it to be stored on any flat surface like a floor, a is table, a desk or a window sill. 
     Accordingly, it can be seen that the various embodiments of the indoor golf swing practice implement allow a golfer to practice indoors in very small spaces with a device that feels like a conventional golf club. The above embodiments are provided as exemplary of the invention and alternative configurations are contemplated and will become clear. For example, the cylindrical end weight could have other shapes, such as a chamfered edge, or an eased or rounded edge. Thus the scope of the embodiments should be determined by the appended claims rather than by the examples given.