Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Ser. No. 61/508,282, filed on Jul. 15, 2011. 
    
    
     BACKGROUND 
     This disclosure relates to golf clubs and more particularly to a golf shaft or shafts having interchangeable heads. 
     Golfing can be difficult to play not just for the skill required but because the golf equipment necessary to play is difficult to lug around a golf course. One who may want to walk the course may not be able to because the fourteen clubs allowed to be carried along with other golf paraphernalia like balls, tees, etc. are simply too heavy to carry. The golfer may then be forced to rent a golf cart and give up the opportunity to walk the course while significantly increasing the cost of the round by renting the cart. 
     Some modular club systems exist in which the club heads are detachable from a shaft. However, the existing systems are difficult to assemble and take apart quickly. 
     SUMMARY 
     According to an embodiment disclosed herein, a golf club system includes a club head and a shaft. The club head has a column extending upwardly therefrom, the column having a tooth extending radially outwardly therefrom, the tooth having a first magnet attaching thereto. The shaft has a wall defining a hollow portion that receives the column, the wall having a slot therein the slot having an insertion portion through which the tooth may slide axially and an attachment portion in which the tooth may rotate circumferentially after passing through the insertion portion and a second magnet that engages the first magnet in the tooth after the tooth rotates circumferentially away from the slot. 
     According to a further embodiment disclosed herein, a method of attaching and detaching a shaft from a club head, includes the steps of providing a first club head having a column extending upwardly therefrom, the column having a tooth extending radially outwardly therefrom, the tooth having a first magnet attaching thereto, providing a shaft, the shaft having a slot therein, rotating the tooth circumferentially within the slot about the shaft, and engaging the first magnet of the tooth with the second magnet. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a modular golf system described herein. 
         FIG. 2  is a an exploded perspective view of a disassembled golf club taken along the line  2 - 2  of  FIG. 1 . 
         FIG. 3  is a view of a tooth used in  FIG. 2 . 
         FIG. 4  is a perspective view of a golf bag for use with the modular golf system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 4  illustrate a modular golf system  10 . The golf system  10  includes a shaft  15  and a plurality of club heads  20  including driving iron club head  25 , 3 iron club head  30 , 7 iron club head  35 , 9 iron club head  40 , pitching wedge club head  45  and putter club head  50 . The club heads  20  are each attached to the shaft  15  by a joint  55 . The club heads  20  and the shaft  15  are stored in a lightweight golf bag  60  as will be discussed infra. Other clubs heads such a wedge(s), a driver, a chipper, a hybrid, a wood or other heads used in golfing may be used by utilizing the teachings provided herein. In fact, a utility head such as a ball retriever club head  65  may also be used. A second (or more) upper shaft  70  that may be shorter, longer or extending for use with a belly putter or for the ball retriever club head  65 , or the like, incorporating a joint  55 , may also be included. 
     Each club head  20  includes a club head  20 , a lower shaft  75  and a hosel  80  that connects the lower shaft  75  to the club head  20 . The lower shaft  75  has a flared portion  85  at an end distal from the hosel  80 . The flared portion  85  creates a shoulder  90  that interacts with the upper shaft  15  as will be discussed infra. A keyed portion  95  extends beyond the flared portion  85  and is coaxial with the lower shaft  75 . Each upper shaft  15  includes a grip  100  and an elongated portion  105  that also terminates at the joint  55  as will be discussed infra. 
     The lower shaft  75  of each club head  20  may be longer or shorter than the other club heads given the requirements of the game. For instance, the club heads  20  for the lower numbered clubs are generally longer than the club heads  20  for the higher numbered club heads. So the club head  45  for a wedge has a lower shaft  75  that is shorter than the lower shaft  75  for the nine iron club head  40  which is shorter than the 7 iron club head  35  etc. This is not to say that the lower shafts  75 , as in some golfing systems, cannot be equal in length or different in length in other ways. 
     Referring now to  FIGS. 2 and 3 , the joint  55  is described. The upper shaft  15  terminates in a wider portion  110  than the width of the upper shaft  15 . A hollowed portion  115  in which the keyed portion  95  extends forms a mild interference fit therein such that the keyed portion may be inserted, rotated coaxially and removed. The interference fit can be defined as one in which the key portion may not move if undisturbed in the hollowed portion  115  but will move if force beyond the force gravity is added. An end  120  of the keyed portion  95  may have a chamfer  117  to allow easier insertion into the hollowed portion  115 . The keyed portion  95  includes a column  125  that extends beyond and coaxially with the shoulder  90 . 
     A tooth  130  extends radially outwardly from the column  125  that fits in the hollowed portion  115 . The tooth has a width W 1 , a height H 1  and a length L 1 . A first magnet  135 , which may be permanent and made of a durable alloyed rare earth material including neodymium, or the like, is attached by cementing or the like, into place in an indentation  140  in a side  145  of the tooth  130 . As shown in  FIG. 3A , the first magnet  135  is recessed into the indentation  140  to minimize a force of a golf club swing on the first magnet  135 . Such force would be carried by the tooth  130  to wall  170  in the wider portion  110 . The first magnet  135  may also be cemented to the side  145  and not be placed in an indentation  140 . 
     Referring back to  FIG. 3 , the wider portion  110  of the elongated portion  105  has a slot  150 . The slot has a width W 2  that is roughly equal to the width W 1 , and a height H 2  that is equal or greater than the height H 2  so that if the tooth is inserted in the slot  150 , the tooth height H 1  is equal to a the height H 2  of the surface  155  of the wider portion  110  or extends there beyond such that a mild interference fit as defined above exists. The slot  150  is defined by an insertion portion  160  extending through the wider portion  110  and an open attachment portion  165  that extends circumferentially around and through the wider portion  110  from the insertion portion  160 . The insertion portion  160  has a length L 2  that forms a mild interference fit, as above, with the length L 1  of the tooth  130 . 
     The slot attachment portion  165  terminates in a wall  170  of the wider portion  110 . A second magnet  175 , which may also be permanent, is attached within a recess  180  in the wall  170 . As above, the second magnet  175  may be recessed in the recess  180  or attached to the wall  170 . One of the first magnet  135  and the second magnet is arranged so that its positive pole faces away from the wall  170  and the other of the first magnet  135  and the second magnet is arranged so that its negative pole faces away from the side  145  of the tooth  130 . The first and second magnets  135 ,  175  will then attract each other during operation because positive pole and a negative pole attract one another. The joint  55  is defined by: the hollowed portion  115  of the wider portion  110 , the slot  150 , and the second magnet  175  in the wall  170  in the shaft  15 ; and by the tooth  130 , the first magnet  135 , the column  125 , the shoulder  90 , and the flared portion  85  of the club head  20 . 
     To mount a club head  20  to a shaft  15 , a golfer chooses a club head  20  for a required shot or other particular use. For instance, if the required shot is under one hundred yards, the golfer may choose a wedge club head  45  and if the ball is on a green (not shown), the golfer may choose a putter club head  50 . The golfer grasps the putter club head  50 , inserts the column  125  within the hollowed portion  115 , aligns the tooth  130  with the insertion portion  160  of the slot  150 , slides the tooth through the insertion portion  160  until the tooth contacts the wider portion and until the shoulder  90  contacts the wider portion  110  (which happens simulataneously), and rotates either the club head  50  or the shaft  15  so that the tooth moves circumferentially in the attachment portion  165  of the slot  150  until the side  145  of the tooth  130  engages the wall  170  in the wider portion  110 . At this point the first and second magnets  135 ,  175  ensure that the tooth  130  does not disengage from the wall  170 . In the instant example, the tooth  130  rotates counter-clockwise relative to the shaft  15 , so that impact with a golf ball (or turf or sand or a ball washer—not shown) by a club head  20  does not cause a club head  20  to disengage the magnets  135 ,  170  for a right-handed golfer. As one of ordinary skill in the art can appreciate, if a golfer is left-handed, the slot  150  would be arranged so that clockwise rotation of the tooth  130  is required. 
     Once a shot is completed and another club head  20  is desired, e.g., the golfer is done putting and is ready to select another club head  20 , the process is reversed. The right-handed golfer, the club head  50  is rotated clockwise relative to the shaft  15  so that the tooth  130  moves thereby disengaging the magnets  135 ,  175  and the tooth engages wide portion wall  185 . The tooth  130  is then slid through the insertion portion  160  and the column  125  disengages the hollowed portion  115 . Another club head, such as driving iron club head  25  may be coupled to the shaft  15 . 
     Referring now to  FIG. 4 , golf bag  60  is shown. The bag  60  has a shoulder strap  200  attached at either end to a body  205 . Though the body  205  is shown as cylindrical, other shapes are contemplated herein. The bag  60  has a plurality of holster-shaped outer pockets  210  attached to an outer surface  215  of the bag  60 . The interior  220  of the bag  60  is hollow so that the shaft  15  or other shafts may be carried therein. The bag is lighter because the golfer does not have to carry fourteen shafts due to the unique nature of the joint  55  described herein, only one shaft  15  is necessary for a golfer to carry. The bag  60  may have other pockets  230  to carry balls, tees, markers, divot tools, distance lens, etc. (not shown) as may be necessary. 
     The pockets  210 , which may be holster-shaped, have an elongated section  235  for fitting the lower shafts  75  therein and a wider portion  240  extending above the elongated section  235  for fitting the club head  20  therein. To protect the club heads  20  from the elements, the wider portion may be capped by a cover  245  that attaches to the outside surface  250  of the pocket  210  by a zipper  255 . Indicia  260  may be placed on each pocket  210  to enable a golfer to properly store and select each club head  20 . The elongated sections  235  are sized to accommodate a length of each lower shaft  75 . In other words, the elongated sections  235  are longer for a 3 iron club head  30  than for a 9 iron club head  40 . The pockets may be aligned (e.g., for pockets with club heads for a 2, 3, 7 and 9 iron) in such a way that the lengths of the lower shafts  75  for each column of pockets equal the lengths of the lower shafts  75  for other aligned pockets (as for the club heads for a driver “D”, 4, 6, pitching wedge “PW” that may equal the club heads for the 2, 3, 7 and 9 iron) to maximize space on the surface  250  of the bag  60 . The pockets  210  may also interleave such that pockets  210  aligned in a first column  260  may have each pocket with the wider portion  240  extending to the right (as seen in  FIG. 4 ) and the second column  270  may have pockets  210  with their wider portions  275  extending to the left and below the wider portions  240  of the first column  260  to create a staggering of the pockets  210  in the first column  260  and the second column  270 . This staggering allows for the placement of more club heads  20  on the bag  60 . 
     The applicants have discovered that the prior art systems have mechanical connections that tend to wear over time creating tolerances (slop) in the joints. This slop may cause the joints to loosen thereby lessening the feel a golfer expects when hitting the ball because of relative motion in the joints. The golfer may also lose power because of energy absorbed in the joint due to relative motion therein. The joints may also cause noise. Because the embodiments shown herein use first and second magnets, which may be permanent, even if the mild interference fits are loosened by wear, the first and second magnets  135 ,  175  will keep the tooth  130  in contact with the wider portion  110  so that there is minimal or no movement in the joint  55  to enhance feel, minimize noise, maximize power and maximize the golfing experience over time. 
     Although an example embodiment has disclosed, a worker of ordinary skill in the art would recognize that certain modifications would come within the scope of the claims. For example, any feature of the various examples described above may be used with any other feature of a different example. For that reason, the following claims should be studied to determine their true scope and content.

Technology Category: a