Patent Publication Number: US-2009233729-A1

Title: Vibration reducing golf club

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 97109127, filed Mar. 14, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a vibration reducing golf club. 
     2. Description of Related Art 
     Along with the progress of technology, material culture and life quality are gradually improved, and sports and leisure activities become fashionable. Golf, used to be a noble game played by nobility, is popularized therewith. More and more people of all age groups and different genders get involved in the golf game, and most of them are golf lovers. Currently, the number of people involved in the golf is increasing abruptly. 
     In Taiwan area, the number of manufacturers of the golf equipments grows increasingly, and the techniques and export amounts are progressively improved. In recent years, manufacturers of the golf club continuously bring in new materials and new techniques to improve the quality and accelerate the production of the golf clubs. Among the golf clubs, the carbon fiber golf club, made of a composite material and characterized by “light, thin, elastic, and flexible” etc., is developed and gradually warmly welcomed by the international market. Many manufacturers accept the appointments from the international famous sports brand to manufacture and supply the golf equipments, and become one of the world&#39;s largest exporters. 
     In the golf game, in addition to the techniques and stability, properties of the golf clubs are also one of the factors determining the win or lose of a game. As the golfers pay more attention to the feeling of golf swing, the design and fabrication of the golf clubs increasingly become important. Therefore, the manufacturers are trying hard to provide the golfers a better design of the golf equipments with higher performance. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to provide a vibration reducing golf club, so as to achieve the effect of controlling the vibration of the golf club. 
     The present invention provides a vibration reducing golf club, which includes a club main structure and a plurality of piezoelectric materials. The club main structure includes a club shaft and a ball head. The club main structure can sustain the mechanical energy resulting from the swing of the club shaft and collision between the ball head and a golf ball and produces bending deformation and vibration. The piezoelectric materials are adhered to the club shaft. When the club shaft undergoes mechanical deformation, the piezoelectric materials transform the energy of mechanical deformation into an electrical energy, thereby producing a voltage output. Thus, the vibration energy of the club shaft can be consumed. Therefore, the vibration reducing performance can be obtained by reducing the vibration of the club shaft. 
     The vibration reducing golf club in the present invention further includes a control module and an energy storage module. The control module includes a conductive circuit configuration and a control circuit configuration. The conductive circuit configuration cross-connects the piezoelectric materials. The control circuit configuration is used to control the voltage output and transmission after one of the piezoelectric materials transforms the mechanical energy into an electrical energy, and to apply the produced electrical energy to another piezoelectric material, so as to transform the electrical energy into the mechanical energy. The energy storage module is used to provide the electrical energy required by the control module. 
     In the present invention, the piezoelectric materials are adhered to the club, and produce the electromechanical coupling effect to achieve the effect of controlling the vibration of the golf club. Further, the energy storage device may be added to store the piezoelectric energy transformed by the piezoelectric materials. In addition, the present invention utilizes a converse piezoelectric effect of the piezoelectric materials to transform the electrical energy into the mechanical energy, so as to release a power in forward direction of the collision, thereby enhancing the force for hitting a golf ball. After the collision, a force in opposite direction of the vibration of the club shaft is released by the converse piezoelectric effect of the piezoelectric materials, so as to resist and consume the vibration of the club shaft, thereby achieving better vibration reducing effect. 
     In order to the make aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  is a schematic structural view of a vibration reducing golf club according to a first embodiment of the present invention. 
         FIG. 1B  is a partial cross-sectional view of  FIG. 1A . 
         FIGS. 1C and 1D  are schematic views showing wire connections of the piezoelectric materials of the vibration reducing golf club according to the first embodiment. 
         FIG. 2  is a curve diagram showing vibration velocity and frequency response taken at an 80 cm position from a tip on a club shaft of the vibration reducing golf club according to the first embodiment. 
         FIG. 3  is a schematic structural view of an intelligent golf club according to a second embodiment of the present invention. 
         FIG. 4  is a circuit diagram of an energy storage device of the intelligent golf club according to the second embodiment. 
         FIG. 5  is a schematic view showing a feedback vibration reducing system of the intelligent golf club according to the second embodiment. 
         FIG. 6  is a schematic view showing a conductive circuit configuration of the intelligent golf club according to the second embodiment. 
         FIG. 7  is a schematic view showing manufacturing processes of an inner adhering piezoelectric material according to the second embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1A  is a schematic structural view of a vibration reducing golf club according to a first embodiment of the present invention.  FIG. 1B  is a partial cross-sectional view of  FIG. 1A . 
     Referring to  FIGS. 1A and 1B , the vibration reducing golf club  100  of the first embodiment includes a club main structure  102  and a plurality of piezoelectric materials  104   a,    104   b,    104   c,  and  104   d.  The piezoelectric materials  104   a,    104   b,    104   c,  and  104   d  may be a single crystal piezoelectric material, such as quartz, lithium niobate, and lithium tantalate; a thin film piezoelectric material, such as zinc oxide; a polymer piezoelectric material, such as polyvinylidene difluoride (PVDF); a ceramic piezoelectric material, such as barium titanate and lead zirconate-titanate; and any combinations of the above materials, and preferably the ceramic piezoelectric material. The club main structure  102  includes a club shaft  106  and a ball head  108 . The club shaft  106  is, for example, an iron shaft, a wood shaft, or a composite material shaft (for example, a carbon fiber club). The club main structure  102  can sustain the mechanical energy resulting from the swing of the club shaft  106  and the collision between the ball head  108  and a golf ball (not shown), and produces vibration and bending deformation. The piezoelectric materials  104   a,    104   b,    104   c,  and  104   d  are connected in parallel and adhered to the club shaft  106 , and the wire connection manner is shown in  FIGS. 1C  and  1 D. 
       FIGS. 1C and 1D  are schematic views showing wire connections of the piezoelectric materials of the vibration reducing golf club according to the first embodiment. In the figures, only the club shaft  106  and the piezoelectric materials  104   a  and  104   c  disposed correspondingly are shown. If the polarities of the sides of the piezoelectric materials  104   a  and  104   c  facing the club shaft  106  are positive and negative respectively, this arrangement direction is referred to as forward direction (as shown in  FIG. 1C ). If the polarities of the sides are both negative, this arrangement direction is referred to as reverse direction (as shown in  FIG. 1D ). When swinging the golf club (equivalent to that the club shaft  106  undergoes the mechanical deformation), the piezoelectric materials  104   a  and  104   c  function as sensors for sensing the deformation of the club shaft  106 , so as to transform the energy of mechanical deformation into the electrical energy, thereby producing a voltage output (i.e. the direct piezoelectric effect). Thus, the piezoelectric materials  104   a  and  104   c  on two sides of the club shaft are polarized. When the piezoelectric materials  104   a  and  104   c  adhered to the two sides of the club shaft  106  have the same polarities, the polarization directions are the same. Therefore, if the piezoelectric material  104   a  and another piezoelectric material  104   c  are cross-connected with their positive electrodes connected and their negative electrodes connected respectively, a voltage feedback is generated therebetween, which is equivalent to connecting the piezoelectric materials  104   a  and  104   c  in parallel. The piezoelectric material  104   a  is an actuator, the produced voltage makes the corresponding piezoelectric material  104   c  to produce the opposite deformation, thereby achieving the effect of controlling vibration. 
       FIG. 2  is a curve diagram showing vibration velocity and frequency response taken at an 80 cm position (centre of the piezoelectric material) from a tip on a club shaft. The velocity in the vibration velocity response diagram is in the unit of dBm/s, and the value may be converted by the following equation: 
         dBv= 20 log 10 ( v ) 
     where v is the vibration velocity at the measuring point of the club, and dBv is the vibration velocity after being converted into the log dimension. It is apparent from  FIG. 2  that the amplitude of the vibration of the vibration reducing golf club having the piezoelectric materials with their wires cross-connected in parallel is further reduced as compared with that without the wires cross-connected in parallel. 
     In the first embodiment, the piezoelectric materials of the vibration reducing golf club may also be adhered at the following positions on the club shaft. 
     1. The piezoelectric materials may be adhered at positions in a larger deformation region of the resonant frequency mode of the club shaft in the desired vibration reducing frequency scope, so as obtain better vibration reducing effect. The larger deformation region of the club shaft varies according to different resonant frequencies. Therefore, the piezoelectric materials may be adhered in several regions. 
     2. The piezoelectric materials may also be adhered to an outer surface of the club shaft or to an inner tube wall of the club shaft as required. 
     3. The piezoelectric materials may be a combination of several units adhered to the club shaft along its axis as required. 
     4. The piezoelectric materials may be adhered to the club shaft along its axes at different angles as required. The polarities of the piezoelectric materials adhered to the club shaft along its axes at different angles are arranged in forward direction or reverse direction. 
     5. The piezoelectric materials may be embedded in grooves of the club shaft as required. 
     6. When the club shaft is a composite material shaft, the piezoelectric materials may be encapsulated by a lamination layer of the composite material shaft as required. 
     To sum up, the position where the piezoelectric materials are adhered may be one selected from one or any combinations of the above positions. 
       FIG. 3  is a schematic structural view of a vibration reducing golf club according to a second embodiment of the present invention. 
     Referring to  FIG. 3 , the vibration reducing golf club  300  of the second embodiment includes a club main structure  302 , a plurality of piezoelectric materials  304 , a control module  306 , and an energy storage module  308 . The materials of the piezoelectric materials  304  may be selected similarly to the maimer discussed in the first embodiment. The club main structure  302  includes a club shaft  310  and a ball head  312 . The club main stricture  302  can sustain the mechanical energy resulting from the swing of the club shaft  310  and the collision between the ball head  312  and a golf ball (not shown), and produces bending deformation and vibration. The selection of the club  310  can refer to that of the first embodiment. The piezoelectric materials  304  are adhered on the club shaft  310 . When the club shaft  310  undergoes the mechanical deformation, the piezoelectric materials  304  transform the energy of mechanical deformation into the electrical energy, thereby producing a voltage output (the piezoelectric materials are referred to as the piezoelectric sensors herein). When the piezoelectric materials  304  undergo the electrical energy load, the piezoelectric materials  304  transforms the electrical energy into-the mechanical deformation output (the piezoelectric materials are referred to as the piezoelectric actuators herein). The positions of the piezoelectric materials  304  adhered to the club shaft  310  of the vibration reducing golf club are similar to those discussed in the first embodiment. Further, only the connection relation between the control module  306 , the energy storage module  308  and the piezoelectric materials  304  is shown in  FIG. 3 , which should not considered as indicating the practical positions of them in the vibration reducing golf club  300 . The energy storage module  308  is used to provide the electrical energy required by the control module  306 . For example, the energy storage module  306  may be a battery or an energy storage device that stores the electrical energy output by the piezoelectric materials  304  into a rechargeable cell, as shown in  FIG. 4 . 
       FIG. 4  is a circuit diagram of an energy storage device of the vibration reducing golf club according to the second embodiment. The same reference numbers used in  FIGS. 3 and 4  refer to the same parts. Referring to  FIG. 4 , the energy storage device  400  includes a rectifier circuit  401 , a capacitor  402 , and a rechargeable cell  403 . The piezoelectric materials  304  transform the mechanical energy into the electrical energy under the direct piezoelectric effect, thereby producing a voltage output. The voltage is applied across a rectifier circuit  401 , for example a bridge diode, and is rectified to a direct current, and then output to the capacitor  402 . The electrical energy may be first charged in the capacitor  402 , and finally output and stored in the rechargeable cell  403 . The capacitance of the capacitor  402  must match the input voltage, and the rechargeable cell  403  may be nickel-hydrogen cell, lithium cell, or any other rechargeable cell. The energy storage device  400  may be used to store the electrical energy transformed by the piezoelectric materials  304  during the swing of the club into the rechargeable cell  403 , and the stored electrical energy may be used in the subsequent control and reducing of the vibration. 
       FIG. 5  is a schematic view showing a feedback vibration reducing system of the vibration reducing golf club according to the second embodiment. In  FIG. 5 , the energy storage device is omitted. Referring to  FIG. 5 , the control module  306  includes a conductive circuit configuration  500  and a control circuit configuration  501 . The conductive circuit configuration  500  cross-connects the piezoelectric materials  304 . The control circuit configuration  501  is used to control the voltage output and transmission after one of the piezoelectric materials (sensors)  304  transforms the mechanical energy into an electrical energy, and to apply the produced electrical energy to another piezoelectric material (actuator)  304 , so as to transform the electrical energy into the mechanical energy. In addition, the control circuit configuration  501  may also be a vibration control configuration, capable of releasing the voltage stored in the rechargeable cell ( 403  in  FIG. 4 ) through a control circuit (not shown) after the ball head ( 312  in  FIG. 3 ) hits the golf ball (not shown), and leading the voltage to the piezoelectric materials (actuators)  304 , so as to transform the electrical energy into the mechanical energy, thereby releasing a force to resist the deformation of the club shaft  310 . Also, in order to achieve a better vibration reducing effect, the vibration control configuration may further include an amplifier, for amplifying the voltage output by the piezoelectric materials (sensor)  304 . In addition, the control circuit configuration  501  can also include a power driving circuit configuration, for releasing a force when the ball head hits the golf ball (not shown), so as to increase the flight kinetic energy of the golf ball. For example, when the piezoelectric materials are deformed to transform the mechanical energy into the electrical energy to produce the voltage output, the power driving circuit triggers the timer to start counting. After a period of time (i.e. starting when the club shaft  310  begins to deform and ending when the club shaft  310  restores and the ball head finishes hitting the golf ball), the voltage stored in a rechargeable cell ( 403  of  FIG. 4 ) is released through a control circuit, and is led to one of the piezoelectric materials (actuators)  304 , such that the electrical energy is transformed into the mechanical energy, so as to output a power to drive the club shaft  310 , thereby enhancing an impact force of the ball head  312  when hitting the golf ball. 
       FIG. 6  is a schematic view showing a conductive circuit configuration of the vibration reducing golf club according to the second embodiment. Referring to  FIG. 6 , if the polarities of the sides of the piezoelectric materials  304  facing the club shaft  310  are positive and negative respectively, this arrangement direction is referred to as forward direction. If the polarities of the sides are both negative, this arrangement direction is referred to as reverse direction. Therefore, the piezoelectric materials in  FIG. 6(   a ) are connected in parallel in forward direction, the piezoelectric materials in  FIG. 6(   b ) are connected in series in forward direction, the piezoelectric materials in  FIG. 6(   c ) are connected in parallel in opposite directions, and the piezoelectric materials in  FIG. 6(   d ) are connected in series in opposite directions. Therefore, if the piezoelectric materials  304  are connected in parallel, the produced voltage makes corresponding piezoelectric materials to produce opposite deformation tendencies, thereby restraining the original deformation and achieving the vibration reducing effect. On the contrary, if two piezoelectric materials  304  are connected in series, the potential energy of the voltage produced by the two piezoelectric materials may be added, thereby achieving a better energy storage effect. In addition, the conductive circuit configuration may further include a switching switch (not shown), for switching the control circuit configuration ( 501  in  FIG. 5)  to the vibration control configuration or the power driving circuit configuration. 
     The adhesion manner of the piezoelectric materials  304  of the second embodiment may be an outer adhesion, inner adhesion, or encapsulating manner. Among the manners, the outer adhesion and the inner adhesion will not affect the original golf club manufacturing process. In  FIG. 7 , the piezoelectric materials  304  are adhered, for example, in the inner adhesion manner, which is only an example for fabricating the piezoelectric materials of the second embodiment and is not intended to limit the fabricating method of the structure of the present invention. 
       FIG. 7  is a schematic view showing manufacturing processes of an inner adhering piezoelectric material according to the second embodiment. Referring to  FIG. 7 , the composite material of the second embodiment may be formed by six piezoelectric strips  700  having a size of 50 mm*2 mm*0.3 mm, four conductive copper foils  702  having a size of 160 mm*1.5 mm*14 μm, and two glass fiber/epoxy resin prepreg cloths  704  having a size of 160 mm*10 mm. The molds required by the manufacturing process are divided into an inner mold  706  and an outer mold  708 . The inner mold  706  is made of a high molecular material, for example, PTFE, Teflon, or any other fluoro polymer material, and has the characteristics such as fine release and high expansion coefficients. The outer diameter of the inner mold  706  equals to the inner tube diameter of the club shaft minus twice the thicknesses of the piezoelectric strips  700 , the conductive copper foils  702 , and the prepreg cloths  704 . The outer mold  708  is a metal mold made of an aluminium or a steel material, and the inner diameter thereof equals to the inner tube diameter of the club shaft. 
     The manufacturing processes of  FIG. 7  are described as follows. 
     In Step  1 , one glass fiber/epoxy-resin prepreg cloth  704  is adhered on a surface of the inner mold  706  made of the fluoro polymer material. 
     In Step  2 , each of the conductive copper foils  702  is respectively adhered at the symmetrical position (0°/180° or 90°/270°). 
     In Step  3 , three piezoelectric strips  700  are placed on each of the conductive copper foils  702 . 
     In Step  4 , the conductive copper foils  702  are respectively placed on the piezoelectric strips  700 , and an insulating material is coated between the piezoelectric strips  700 , so as to isolate the upper and the lower conductive copper foils  702 . 
     In Step  5 , one glass fiber/epoxy resin prepreg cloth  704  is adhered to the conductive copper foils  702 . 
     In Step  6 , they are encapsulated by one OPP thin film encapsulates, and placed into the outer mold  708  of moulded metal. 
     In Step  7 , the outer mold  708  is placed into a hot press machine, and is pressurized to 2 kg/cm 2  and heated for 30 minutes in an environment of 135° C. 
     In Step  8 , the outer mold  708  is cooled down, then opened, so as to remove the OPP thin film and take out the inner mold  706 , thus obtaining the moulded piezoelectric unit. 
     In Step  9 , a solvent type epoxy adhesive curable at 130° C. is coated on the surface of the piezoelectric unit, and then the piezoelectric unit is laid for the solvent evaporating to dry. 
     In Step  10 , the piezoelectric unit is pushed into the appropriate position in the club shaft by a fixture. 
     In Step  11 , the club is placed into the oven and heated at 135° C. for 30 minutes, thus finishing the assembly processes of the inner adhering piezoelectric materials. 
     To sum up, the present invention uses the piezoelectric materials to transform the mechanical load into the voltage output, or transform the voltage input into the force output, and thus having the advantages of high piezoelectric constant, quick response, small volume, and no electromagnetic interference, etc. Therefore, when applied to the golf club, the present invention alleviates the vibration resulting from the collision between the golf club and the golf ball, and particularly, the violent vibration caused by failing to hit the sweet spot. In addition, the present invention also employs the control module and the energy storage module to control the piezoelectric materials, so as to achieve a vibration reducing golf club capable of reducing the vibration and/or enhancing the hitting force. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.