Abstract:
A golf club shaft is formed of an upper tubular body and a lower tubular body, which are different in flexibility from each other and are coaxially coupled by a connection rod in conjunction with a washer.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to a golf club, and more particularly to a golf club shaft which is formed of a plurality of tubular bodies different in flexibility from one another.  
         BACKGROUND OF THE INVENTION  
         [0002]    In general, a golfer purchases a golf club on the basis of the golf club flexibility that is most suitable to the golfer. The conventional golf club shaft is generally made of a flexible and lightweight fiber composite material. Such a golf club shaft has a greater ball-carrying capability. For a professional golfer or an ordinary golfer with strong arms, a metal golf club shaft is preferred. In addition to the metal golf club shaft, a golf club shaft made of a rigid material is also preferred. The rigid golf club shaft is more precise in terms of the ball striking point. The rigid golf club shaft has a better ball controllability at the expense of the ball-carrying distance. On the contrary, the flexible club shaft has a better ball-carrying distance at the expense of ball-striking precision.  
           [0003]    The U.S. Pat. No. 5,735,752 discloses a golf club shaft having an insert. The insert comprises a spiral midsegment and two couplers extending respectively from two ends of the midsegment for coupling a shaft or head. The insert serves to adjust the flex point of the shaft. In addition, the insert controls the center of gravity of the shaft and reduces the impact at the expense of the ball-carrying capability and the ball controllability.  
         SUMMARY OF THE INVENTION  
         [0004]    The primary objective of the present invention is to provide a golf club shaft which is formed of tubular bodies different in flexibility. The golf club shaft is characterized by a stable ball-striking point and a greater ball-carrying distance.  
           [0005]    The golf club shaft of the present invention is formed of an upper tubular body and a lower tubular body which is coaxially coupled with the upper tubular body. The upper and the lower tubular bodies are different in flexibility from each other. The tubular body of a greater flexibility is responsible for improvement on the ball-carrying distance of the golf club shaft. The tubular body of a smaller flexibility accounts for the stable ball-striking point of the golf club shaft. The two tubular bodies are coupled by a connection rod, with both ends of the connection rod being inserted into the tubular bodies. A protective washer is disposed between the two tubular bodies.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 shows a plan view of a first preferred embodiment of the present invention.  
         [0007]    [0007]FIG. 2 shows an enlarged sectional view of a portion of the circle “A” as shown in FIG. 1.  
         [0008]    [0008]FIG. 3 shows an exploded view of the circle “A” portion as shown in FIG. 1.  
         [0009]    [0009]FIG. 4 shows a schematic view of a second preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0010]    As shown in FIGS.  1 - 3 , a golf club shaft  10  embodied in the present invention comprises an upper tubular body  20 , a washer  30 , a lower tubular body  40 , and a connection rod  50 .  
         [0011]    The upper tubular body  20  is of a tapered construction and is made of a carbon fiber material and a reinforcing metal filament.  
         [0012]    The washer  30  is made of aluminium, tough metal, or engineering plastic material. The washer  30  has an outer diameter which is corresponding to the outer diameter of the tip or the upper tubular body  20 . The washer  30  is pressed against the surface of the top of the upper tubular body  20 .  
         [0013]    The lower tubular body  40  is of a tapered construction and has a length and an outer diameter, which are corresponding to about one seventh of the dimension of the tip of the conventional golf club shaft. The lower tubular body  40  is made of a carbon fiber material and is greater in rigidity than the upper tubular body  20 . The outer diameter of the large end of the lower tubular body  40  is corresponding to the outer diameter of the washer  30 . The large end of the lower tubular body  40  is pressed against by the washer  30 . The lower tubular body  40  is coaxial with the upper tubular body  20 .  
         [0014]    The connection rod  50  is used to couple the two tubular bodies  20  and  40  and is made of a resilient steel or other metal of a predetermined flexibility. The length of the connection rod  50  is about 4 cm. The connection rod  50  has an outer diameter corresponding to the hole diameter of the middle hole  22  of the upper tubular body  20  and the hole diameter of the middle hole  42  of the lower tubular body  40 . The connection rod  50  is concealed in the shaft such that the connection rod  50  is located in the center of the washer  30 , and that both ends of the connection rod  50  are inserted respectively into the middle hole  22  of the upper tubular body  20  and the middle hole  42  of the lower tubular body  40 . The coupling of the tubular bodies  20  and  40  is reinforced by an adhesive. The connection rod  50  is provided in the periphery thereof with a knurled portion  52 , in which the adhesive is held. The knurled portion  52  serves to provide additional friction. The connection rod  50  is further provided in one side thereof with a trench  54  extending along the longitudinal direction of the connection rod  50 . The trench  54  serves to allow the escape of air contained in a head which is connected with the connection rod  50 .  
         [0015]    In light of the upper tubular body  20  being greater in rigidity, the shaft  10  is relatively stable at the time when the head hits a ball. As a result, the ball-hitting point of the head is not excessively deviated. In view of the lower tubular body  40  being greater in elasticity, the shaft has a greater ball-carrying capability. In addition, the metal connection rod  50  lowers the center of gravity of the shaft  10  of the present invention, thereby resulting in enhancement of the shaft-swinging inertia. As a result, the shaft  10  of the present invention has a greater ball-carrying capability.  
         [0016]    The washer  30  also prevents the direct contact between the two tubular bodies  20  and  40 . As a result, the crack of the tubular bodies  20  and  40  is averted. The contact surfaces of the washer  30  and the tubular bodies  20  and  40  are coated with an adhesive.  
         [0017]    The length ratio of the upper tubular body  20  and the lower tubular body  40  is about 6:1, which is not exclusive. The coupling point of the tubular bodies  20  and  40  is preferably located in the lower portion of the shaft.  
         [0018]    As shown in FIG. 4, a shaft  60  of the second preferred embodiment of the present invention comprises an upper tubular body  61 , a lower tubular body  62 , a washer  63  held between the two tubular bodies  61  and  62 , and a connection rod  64  coupling the two tubular bodies  61  and  62 . The upper tubular body  61  is made of a carbon fiber material and is thus greater in flexibility than the lower tubular body  62  which is made of the carbon fiber material and a metal material in the form of filaments. In addition to the carbon fiber material, other fiber-reinforced composite materials may be used.