Abstract:
A mobile golf practice device adapted for attachment to the bumper of a standard electric golf cart which allows a golfer to practice his or her stroke with the selected club, proximate the actual shot to be played. The device has an L shaped rigid shaft fixed attached to the cart bumper on one end and carrying a swivel on the other. A flexibly tethered golf ball is attached to the swivel such that the ball moves freely in a arc about the shaft when struck. By striking a golf ball and observing the motion of the ball as it orbits the shaft as well as the number of orbits the golfer can judge the effectiveness of the proposed shot in respect to his actual lie of the course.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to mobile golf practice devices which assist golfers in improving the accuracy of their stroke; and, more particularly, to a vehicle mounted device which allows a golfer to observe the correctness of his swing. 
     2. Description of the Related Art 
     Golf has become a national pastime. The paraphernalia that is available to the golfer is second to none. Although golf is very popular, and does not require a great deal of physical endurance, it is nevertheless a game of skill. Therefore, a number of devices have been offered to improve the golfer&#39;s swing, as well as his contact with the ball. For example, ergonomic putters are designed with the shaft attached to the head in the center of club, rather than at the end. Resin and graphite have replaced the old metal shaft. Adjustable club heads actually allow the golfer to adjust the head angle to correct for a slice or hook. 
     No matter how sophisticated the equipment gets, the fact of the matter is that a player&#39;s score is impacted most greatly by his swing and thus the way in which he addresses and strikes the golf ball. Therefore, many golf practice devices have been designed to allow stance and stroke practice at locations other than the golf course or the driving range. Some of these practice devices involve computerized imagery which use complicated software to simulate the path of the ball after it is hit. These are expensive and bulky. Others are more simple in design and attach to stationary objects or are attached to bases adapted to be driven into the ground. These devices incorporate, for example wiffle balls (hollow balls with holes in the surface), as well as actual golf balls that are tethered to extensions or arms such that they can be hit without having the golfer chase or otherwise retrieve the ball. 
     Thus, golf practice devices that attempt to help players improve their proficiency are well known in the art. Most of these devices are designed for use at home or at work. None of these practice devices are designed for use by the golfer near the hole that is about to be played i.e. is mobile so it can be used in the field of play prior to the golfer actually taking a shot. Thus, they cannot be set up so they are mobile to give a golfer the chance to practice under actual playing conditions with the club he or she is about to use. 
     For example, U.S. Pat. No. 2,929,632, issued to Moffatt shows a device for helping golfers practice their swing. The device has a hollow, golf-ball sized ball hung by a cord from one end of an L-shaped bar. The other end of the bar is firmly attached to the ground by a base plate that is anchored in the soil by two spikes on the bottom side of the plate. The Moffatt device provides a golfer with a device for practicing his or her stroke, but it is not mobile and can only be used in designated practice areas of a golf course. Golf courses limit the use of this device because of the holes the spikes create when they are pounded into the turf. Moreover, the device is cumbersome, and cannot be easily carried by a golfer from hole to hole during actual play. 
     While several patents have been issued on similar devices, none of these improved inventions can be used on the actual field of play. For example, UK Patent No. 1,263,269, issued to Hall discloses a mechanism which records and displays the number of times a struck ball rotates around the horizontal end of the L-shaped bar. Since the number of rotations is proportional to the club&#39;s impact force against the ball, golfers are able to estimate the power in their stroke and the distance an untethered golf ball would travel. U.S. Pat. No. 4,932,660, issued to Wang discloses a rotatable and pivotable component. The Wang device has sensors in the component that can record both the angle and force with which the ball leaves the club head. A golfer can use the data provided by the Wang device to make more precise estimates on the force of the stroke and the direction in which a ball travels. 
     None of these golf practice devices allow golfers to practice their stroke under conditions which most closely resemble those of actual play. These devices do not permit golfers to practice their stroke from the approximate location where they must make a shot that counts in the game. Moreover, since these devices are located far from the actual course, golfers must forfeit the opportunity to practice their stroke just before they make the actual shot. Thus, it would be advantageous to have a golf practice device that is fully portable on a golf cart and allows golfers to practice their stroke by striking a golf ball and observing the motion of the ball, yet is proximate the shot being played thus, allowing a golfer to practice from the approximate location where they will make the shot on the course. 
     SUMMARY OF THE INVENTION 
     The present invention provides for a mobile golf practice device which attaches, either removably or fixedly, to a mobile golfing vehicle, such as an electric golf cart. In the broad aspect, a support shaft is mounted upon a golfing vehicle at its one end and rotationally attaches to tethered golf ball on the other such that the golf ball is in position over the ground to be struck as if the ball were in play. In one aspect of the invention, the device attaches to a bumper on a golf cart used to caddy players and equipment from hole to hole on the course. 
     The mobile practice device of the present invention comprises a vehicle attachment means for attaching the device to a vehicle; a support shaft having a first end and a second end with the first end adapted for fixed attachment to the attachment means; and, a golf ball tethering means rotationally attached proximate the second end of the shaft, for allowing the golf ball to orbit the shaft after being struck by the golf club. 
     The vehicle attachment means preferably comprises a plate, and mounting brackets attached to the plate. The mounting brackets are preferably designed to grip the top and bottom sides of a bumper in order to immovably fix the plate to the bumper. The gripping force of the brackets on the bumpers is adjusted by tightening or loosening threaded fasteners that attach the brackets to the plate. The threaded fasteners include screws, bolts, hexagonal nuts and wing nuts. This preferred vehicle attachment means eliminates the need for holes to be placed in the bumper. 
     In another preferred aspect, the vehicle attachment means comprises a C-clamp. The c-clamp has an adjustable tightening lip, and a holding lip facing opposite to the adjustable tightening lip. The vehicle attachment means is immovably attached to the golf cart bumper by tightening down the adjustable tightening lip onto the bumper. Similar to the mounting brackets described above, this preferred attachment means does not require holes to be drilled directly into the bumper. 
     In another aspect, the vehicle attachment means comprises a plate that is immovably fixed to the bumper of a golf cart by at least one fastener. The plate is preferably made from wood, rigid plastic, composite metal, or the like and more preferably, the plate is made from stainless steel or aluminum. The plate is preferably fastened to the golf cart bumper by pins, bolts, screws, or a combination of these fasteners, that are drilled directly into the bumper. The plate may also be adhesively attached to the bumper. 
     The support shaft is preferably bent at a substantially right angle, making a L-shaped, rigid shaft. In this preferred aspect, the first section of the shaft points substantially perpendicular to the ground, and the second section is aligned substantially parallel with the ground and in play position points away from the golf cart. The shaft is attached to the vehicle attachment means, proximate to the first section of the shaft, by any known means for attaching a shaft to a plate, including pins, screws and other fasteners, clamps, and retaining rings. In a preferred aspect, the shaft can be adjusted such that the second section points substantially away from the golf cart, while a golfer is practicing, and points substantially parallel with the golf cart, while the cart is in motion i.e. the shaft swivels from one fixed position to another for storage. 
     In another aspect, a strait, unbent shaft, having a first end and a second end opposite the first, is attached to the vehicle attachment means and the tethering means. In this preferred aspect, the long axis of the shaft is aligned substantially parallel to the ground. The shaft is attached to the vehicle attachment means, proximate to the first end of the shaft by any known means for attaching a shaft to a plate, including pins, screws and other fasteners, clamps, retaining rings, welds, adhesives, and mating threads between the shaft and the plate. The golf ball tethering means is attached to the unbent shaft, proximate to its second end. 
     The shaft, either L-shaped or unbent, can be solid or hollow, and can be made from a wide variety of rigid materials, including wood, composites, plastics, metals or the like. In a preferred aspect, the shaft is made from stainless steel, aluminum, or fiberglass. 
     The golf ball tethering means is preferably flexible but could be rigid. The flexible tethering means is for example, a flexible cord or braided wire having a lower end attached to the ball which is preferably the size of a standard golf ball, and an upper end rotationally attached to the shaft proximate the second end. Preferably the upper end of the tether if fixedly attached to an oblate spool or pulley which prevents the cord from wrapping around the shaft when it is struck and the spool or pulley is rotatably fastened to the horizontal end of the support shaft. In order for the spool to rotate freely on the end of the shaft, a bearing, fixed to the end of the shaft, for example is inserted in the center portion of the spool. In this fashion the inner diameter surface of the spool moves rotatably around the outer diameter surface of the fixed bearing with a minimum of friction. 
     In another preferred aspect, the flexible golf ball tethering means includes a rotatable member and a connecting bar that is attached to the member. The member is mounted on the shaft at approximately the horizontal end of the shaft and rotatable about the long axis of the shaft. The connecting bar has a first end swivelled on the rotatable member and a second end extending downwardly from the rotatable member, where the ball is attached to this second end. In this preferred aspect of the tethering means, when a golfer hits the ball with a club, the ball and connecting bar rotate and pivot about the shaft until the ball loses enough momentum to come to a complete stop. 
     In another aspect the flexible golf ball tethering means comprises a flexible cord attached to a unit formed from a pair of ring shaped grommets, connected together by a tubular sleeve. The grommets are rotatably inserted upon the shaft, proximate the horizontal end of the shaft, and the upper end of the flexible cord is tied around the tubular sleeve. In order to prevent the grommets from sliding across the shaft, or sliding off the end of the shaft, a first and a second laterally spaced retainer are affixed to the shaft on opposite ends of the grommets. In order for the grommets and tubular sleeve to rotate freely about the long axis of the shaft, a first and a second washer, encircling the shaft, are positioned on opposite ends of the grommets, with each washer sandwiched between the end of a grommet and one of the laterally spaced retainers. 
     In still another preferred aspect, the flexible golf ball tethering means includes a flexible cord or rope with an upper end and a lower end. The upper end of the cord is attached to the shaft at approximately the horizontal end, and the lower end of the shaft is attached to the ball. When the ball is struck, the ball orbits the long axis of the shaft until the cord has completely wrapped itself around the shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects, features and advantages of the present invention will be apparent to one skilled in the art, in view of the following detailed description in which: 
     FIG. 1 illustrates a perspective view of a preferred embodiment of the mobile golf practice device of the present invention attached to the bumper of a golf cart; 
     FIG. 2 illustrates a partial cross sectional view of the attachment device shown in FIG.  1  through lines  2 — 2 ; 
     FIG. 3 illustrates an exploded view of the rotationally attaching means of FIG. 1; 
     FIG. 4 illustrates two rotational planes (H and S) of a rotating golf ball that indicate to the golfer that the ball has hooked or sliced; and 
     FIG. 5 illustrates a cross sectional view of another embodiment of the mobile practice device attached to a bumper by means of a C-clamp; 
     FIG. 6 illustrates a cross sectional view of another embodiment of the practice device which has a straight shaft. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, a preferred aspect of the golf practice device  10  of the present invention is shown attached to the bumper  12  of a golf cart. The preferred practice device comprises a bent shaft  14  having a first end  16  pointing towards the ground, and a second end  18  oriented substantially parallel to the ground and facing opposite the golf cart. The shaft  14  has at least one opening  20 , running through the shaft, into which a pin  22  can be inserted for adjusting the vertical position of the shaft with respect to the vehicle attachment means. 
     The preferred vehicle attachment means shown in FIG. 1 includes a plate  24  with a front side, and a back side opposite the front side that faces the bumper  12 . A shaft holding means, comprising a pair of holding brackets  26 , is attached to the front side of the plate  24 . The first end  16  of the shaft  14  slidably inserts into the holding brackets  26  in order to attach the shaft  14  to the plate  24 . As stated above, the vertical position of the shaft  14 , with respect to the plate  24  and holding brackets  26 , is fixed by inserting pin  22  into an opening  20  that is selected from a series of openings vertically aligned along the shaft  14 . The pin  22 , inserted through opening  20 , also prevents the shaft  14  from swiveling inside the holding brackets  26 , thereby fixing the orientation of the second end  18  to face opposite the golf cart. 
     The plate  24  is attached to the bumper  12  by means of mounting brackets (shown in FIG. 2) that clamp the plate  24  to the bumper  12 . The mounting brackets can reversibly fix the plate  24  to the bumper  12  by the reversible tightening of wing nuts  28 , located proximate to the four corners of the plate  24 . Thus, when a golfer is finished using the golf cart, he may detach the practice device from the bumper  12  in order to take the device home. In this preferred aspect, the attachment means makes no permanent marks or holes in the golf cart bumper  12 , when attaching the device to the bumper  12 . 
     The preferred tethering means shown in FIG. 1 includes an oblate spool  30  that is positioned rotatably on the shaft  14 , proximate to the second end  18 . The top end of a flexible cord  32  is tied around the spool  30 , while the bottom end of the cord  32  is attached to a golf ball  34 . When a golfer strikes the golf ball  34  with a golf club, the ball  34  will spin in a orbit around the spool  30  (shown in FIG.  4 ). 
     Referring now to FIG. 2, a cross section of the preferred golf practice device attached to the golf cart bumper in FIG. 1 is shown. The back side  36  of the plate  24  is shown fastened to an upper mounting bracket  38  and a lower mounting bracket  40 . In this preferred aspect, the mounting brackets,  38  and  40 , are fastened to the plate  24  by four threaded bolts that are inserted through the mounting brackets,  38  and  40 , and through the plate  24 . The ends of the threaded bolts that extend through the plate  24  are secured by four nuts  28 . 
     The nuts  28  can be tightened down against the front side  42  of plate  24  for immovably securing the mounting brackets,  38  and  40 , to both the plate  24  and the golf cart bumper  12 . The mounting brackets,  38  and  40 , wrap around the top and bottom sides of the bumper  12  and each have a lip contacting the back side of the bumper  12 . When the nuts  28  are tightened down on the front side  42  of plate  24 , the lips of the mounting brackets,  38  and  40 , are pressed against the back of the bumper  12 , thereby immovably fixing the brackets,  38  and  40 , to the bumper  12 . 
     FIG. 2 also shows a series of vertical aligned openings  20  that extend through the shaft  14 . As described in FIG. 1, the vertical position of the shaft  14 , with respect to the plate  24  and the shaft holding brackets  26 , can be adjusted by the selection of the opening  20  through which a pin (not shown) is inserted. For example, if a golfer desires to move the shaft  14  to the highest possible vertical position with respect to plate  24 , he will insert the pin (not shown) through the opening  20  that is closest to the first end  16  of the shaft  14 . 
     FIG. 2 additionally shows the tethering means of FIG. 1 from another vantage point. The oblate spool  30  of the tethering means is shown rotatably attached proximate to the second end  18  of the shaft  14 . The top end of a flexible cord  32  is tied around the spool  30 , while the bottom end of the cord  32  is attached to the golf ball  34 . 
     Referring now to FIG. 3, a close-up view of the tethering means illustrated in FIG.  1  and FIG. 2 is shown. The tethering means includes an oblate spool  30  which is rotatable about a bearing  44  that is attached to the second end  18  of a shaft  14 . In a preferred aspect, the bearing  44  is a sleeve bearing which has low friction materials, such as Teflon, slide against each other as the spool  30  rotates about the shaft  14 . In another preferred aspect, the bearing  44  comprises ball bearings aligned along the circumference of the bearing  44 , to allow the spool  30  to roll on the ball bearings  44  as it rotates. 
     In this illustrated aspect of the tethering means, the spool  30  is attached to the shaft  14  by inserting a well nut  46  into the hollow second end  18  of shaft  14 , and then fastening a treaded bolt  48 , inserted through bearing center  50 , into the well nut center  52 . The well nut  46  expands and immovably tightens against the inside wall of the shaft  14  as the bolt  48  is threadably inserted into the well nut center  52 . A washer  58  may also be inserted between the bearing  44  and the head of the bolt  48 . 
     Referring now to FIG. 4, two rotational planes are illustrated which indicate that the golf ball  34  has been sliced (the S-plane) or hooked (the H-plane). When a right handed golfer (not shown) strikes the ball  34  from a direction opposite the shaft  14 , such that the ball  34  hooks, then the ball  34 , flexible cord  32  and spool  30  rotate about the shaft  14  in the H-plane. Similarly, when the golfer strikes the ball  34  such that it slices, the ball  34 , flexible cord  32  and spool  30  rotate around the shaft in the S-plane. Alternatively, when a golfer strikes the ball  34  such that it travels in a perfectly strait direction, then the ball  34  will rotate in a plane (not shown) which is perpendicular to the long axis of shaft  14 . Thus, a golfer can determine whether his stroke causes the ball  34  to hook, slice, or travel in a relatively strait-forward direction. 
     Referring now to FIG. 5, another preferred golf practice device  100  is shown attached to a golf cart bumper  112  with a C-clamp type vehicle attachment means. Also shown is a preferred aspect of the tethering means of the practice device which includes a hollow cylindrical body  120  rotatably mounted on a small diameter portion formed on the second end  118  of the shaft  114 , wherein a golf ball  134  is connected to the tethering means by a connecting bar  132  that extends down from a steel ball  128  found inside the hollow cylindrical body  120 . 
     The C-clamp type vehicle attachment means includes a front plate  124 , an upper arm  130  extending from a top edge of the plate  124 , and an anvil  136  extending from the bottom edge of the plate  124 . A threaded rod  138 , having an actuating handle on one end and a pad on the opposite end, extends through a threaded aperture in the upper arm  130 . The practice device  100  is reversibly fixed to the bumper  112  by tightening down the threaded rod  138  on the bumper  112 . 
     A shaft holding sleeve  140  is attached to the front plate  124  of vehicle attachment means. The shaft  114  is attached to the vehicle attachment means by inserting the first end  116  of the shaft  114  into the sleeve  140 , and tightening down a threaded bolt  122 , inserted through a threaded aperture in the sleeve  140 , on the shaft  114 . In this preferred aspect, the vertical position of the shaft  114  with respect to the sleeve  140  can be continuously adjusted along the length of the shaft  114  that is substantially perpendicular to the ground. 
     A small diameter portion of shaft  114 , formed on the second end  118  of the shaft, connects the tethering means. The tethering means attaches to the second end  18  through a bearing  142  that is welded to the cylinder  120  so that the cylinder  120  is journalled on, and revolves around the second end  118  of shaft  114 . A spring  144  is mounted about the small diameter portion in front of the bearing  142 . The first support  148  is cylindrical in shape, and has a concave end facing opposite the second end  118  of the shaft  114 . The small diameter portion of the second end  118  of shaft  114  inserts into a bore centered along the long axis of the first support  148  and is securely fastened to the first support  148  with a treaded bolt  150  that secures end piece  149 . End piece  149  is a t-shaped container the smaller diameter of which has two screw holes to threadably engage bolts  150  in order to retain end piece  149  to the cylinder  120 . 
     The concave side of the first support  148  faces the concave side of the second support  152  in order to form a cradle that swivelly supports the steel ball  128 . The steel ball  128  is attached to the upper end of a connecting bar  132 , which is attached to the golf ball  134  at its lower end. 
     Referring now to FIG. 6, another preferred aspect of the present invention is shown where the shaft  214  is strait rather than bent, and the tethering means comprises a pair of ring shaped grommets,  220  and  222 , rotatably inserted proximate to the second end  218  of the shaft  214 . 
     In this preferred aspect of the present invention, a portion of the shaft  214  proximate to the first end  216  is threaded so that it can be threadably fixed into a threaded opening on the front side of the plate  224 . In this preferred aspect, the plate  224  forms part of the vehicle attachment means, and is immovably clamped to the bumper  212  of a vehicle (not shown) with mounting brackets  238  and  240 , similar to those shown in FIG.  2 . The mounting brackets can reversibly fix the plate  224  to the bumper  12  by the reversible tightening of wing nuts  228 , located proximate to the four corners of the plate  224 . 
     The tethering means of this preferred aspect of the invention includes a pair of ring shaped grommets,  220  and  222 , that are connected together by a tubular sleeve attached to the open center portion of each grommet. A unit consisting of the grommets and the tubular sleeve is positioned rotatably upon the shaft  214 , proximate to the second end  218 . A pair of washers  226 , encircling the shaft  214  and movably mounted thereon are positioned on opposite ends of the grommets  220  and  222 . A pair of laterally spaced retainers  230  are affixed to the shaft  214 , proximate to the sides of the respective washers  226 , opposite the grommets  220  and  222 . In this preferred aspect, the retainers  230  are pins or cotter keys inserted into transversely positioned bores formed in the shaft  214 . 
     A flexible cord  232  is tied around the tubular sleeve between the grommets  220  and  222 . A golf ball  234  is attached to the bottom end of the flexible cord  232 . 
     The mobile golf practice device of the present invention has been exemplified with reference to the various aspects and examples described and illustrated above. By using the description of the present invention found herein, one skilled in the art may be able to design other versions of the mobile golf practice which differ from those illustrated. However, the present invention is not intended to be limited to only the described aspects and examples. Rather, the following claims, and all equivalents of these claims, define the scope of the present invention.