GOLF CLUB HEAD WITH IMPROVED ENERGY TRANSFER AND VIBRATION DAMPENING
Related Patent Applications This application claims priority from U.S. Provisional Patent Application No. 60/062,585, filed October 20, 1997, and U.S. Provisional Patent Application No. 60/097,385, filed August 21, 1998.
Field of the Invention This invention relates to golf club heads, and more particularly, to a golf club head having improved energy transfer and vibration dampening. Background of the Invention
In recent years, the popularity of golf has grown rapidly. Significant time and resources have been spent developing new technology for golf clubs, directed to both the geometry and materials of the shaft and heads. Despite these advances, it is believed that it is possible to develop a superior golf club. In particular, it would be desirable to provide a golf club that increases the distance a golf ball is hit. It would also be desirable to dampen vibrational energy that is conventionally transferred to the user through the golf club when the golf club head strikes the golf ball. The present invention fulfills these needs, and provides further related advantages.
Summary of the Invention Briefly, the present invention provides a golf club head that reduces vibrational energy transmitted to the user from ball impact, and increases energy transfer to the ball, thereby increasing ball distance. These advantages are achieved by forming portions of the golf club head from shape memory alloy. The shape memory alloy (SMA) includes alloys with elements selected from the group comprising: Ni, Ag, Au, Cd, In, Ga, Mn, Cr, Co, C, N, Si, Ge, Sn, Sb, Zn, Nb, Cu, Fe, Pt, Al, and Ti. The shape memory alloy would preferably have superelastic (reversible strain) properties and preferably be able to exhibit stress-induced martensitic phase transformations. It is believed that the ability to transform from an austenitic to a martensitic phase will maximize the damping properties of the alloy Alternatively, the shape memory alloy may be selected and subjected to a heat processing treatment such that it is in the martensitic phase at a desired range of temperatures, in which it is believed the shape memory alloy will be used As a result, a device made of shape memory alloy exhibits superelastic properties when used in the selected range of temperatures, omitting the need to pre- stress the shape memory alloy elements
In addition to vibration dampening, work performed by the shape memory alloy during reversible strain recovery increases the transfer of stored energy from the club head to the ball at impact, thereby enhancing the performance of the club By selection of appropriate dimensional design criteria, golf clubs provided in accordance with the present invention may be made to conform to selected performance requirements, for example, regulations of a professional golf association such as the USGA
Although in a preferred embodiment the entire golf club head is formed from shape memory alloy, such a structure is expensive to manufacture, given the relative high cost of shape memory alloys Therefore, elements of the golf club head made from shape memory alloy preferably include the striking face, a perimeter or body of the club head surrounding the striking face, an attachment to a back surface of the striking face, an attachment to the perimeter or body of the club head surrounding the striking face, and the portion of the club head surrounding and making contact with the shaft of the golf club, known as a hosel
In a preferred embodiment, an insert formed of shape memory alloy is positioned between an inner surface of a striking face of the club, and a club head enclosure The insert extends around a perimeter of the inner surface of the striking face, and may be configured in different manners By way of example, but not limitation, the insert may be solid, grooved, or formed from a length of shape memory alloy hollow tubing
In another preferred embodiment of the present invention, an inner region of the club head enclosure defines a perimeter adjacent an inner surface of the striking face. A plurality of inserts formed from a shape memory alloy are provided in the inner region of the club head enclosure along the perimeter In another preferred embodiment of the present invention, the striking face of the golf club head is made of a shape memory alloy. The golf club head further includes a plurality offeree loading point members or a force loading edge positioned within the club head enclosure, adjacent the inner surface of the striking face. In another preferred embodiment of the present invention, an insert made of shape memory alloy is coupled to the inner surface of the striking face. The insert comprises a plurality of shape memory alloy wires or lengths of shape memory alloy hollow tubing, extending across the inner surface of the striking face. Alternatively, the insert comprises at least one piece of shape memory alloy having a selected shape, thickness, and size, attached to the inner surface of the striking face.
Brief Description of the Drawings The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
FIGURE 1 is a partial cross-sectional front isometric view of a golf club head provided in accordance with a preferred embodiment of the present invention; FIGURE 2 is a top isometric view of the golf club head of FIGURE 1; FIGURE 3 is a partial cross-sectional elevational view of a golf club head provided in accordance with a preferred embodiment of the present invention;
FIGURE 4 is a partial cross-sectional front isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 5 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention; FIGURE 6 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 7 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 8 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 9 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 10 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention; FIGURE 11 is a side elevational view of the golf club head illustrated in FIGURE 10;
FIGURE 12 is a side elevational view of an alternative embodiment of a golf club head provided in accordance with the present invention; FIGURE 13 is a front isometric view of a golf club head provided in accordance with the present invention;
FIGURE 14 is a partially broken away front isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 15 is a top plan view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 16 is a top plan view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 17 is a front elevational view of the golf club head illustrated in FIGURE 16; FIGURE 18 is a top plan view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 19 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 20 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 21 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention;
FIGURE 22 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention; and FIGURE 23 is a partial cross-sectional isometric view of a golf club head provided in accordance with an alternative embodiment of the present invention.
Detailed Description of the Invention A golf club head that reduces vibrational energy transmitted to the user from ball impact and increases energy transfer to the ball on impact is provided in accordance with a preferred embodiment of the present invention. As is discussed in greater detail below, the dampening and energy transfer performance of the golf club head is optimized by providing a golf club head having one or more segments made of shape memory alloy. Alternatively, the entire golf club head is made of shape memory alloy. In a preferred embodiment, the elements made of shape memory alloy (SMA) include alloys with elements selected from the group comprising: Ni, Ag, Au, Cd, In, Ga, Mn, Cr, Co, C, N, Si, Ge, Sn, Sb, Zn, Nb, Cu, Fe, Pt, Al, and Ti. In a preferred embodiment, the shape memory alloy has superelastic (reversible strain) properties, and preferably is able to exhibit stress-induced martensitic phase transformations. Alternatively, the SMA may be selected and subjected to a heat processing treatment such that it is in the martensitic phase at a desired range of temperatures, in which it is believed the SMA will be used. As a result, a device made of SMA exhibits superelastic properties when used in the selected range of temperatures, omitting the need to pre-stress the SMA elements. Although a variety of shape memory alloys may be used, in a preferred embodiment, the shape memory alloy is Nitinol. Nitinol is a known SMA of nickel and titanium.
In a first preferred embodiment, as illustrated in FIGURE 1, a golf club head 10 has a striking face 11 integrally formed with a club head enclosure 14 forming a hosel 33 and rear perimeter body 34. The striking face has an outer surface 12 and an inner surface 13. An insert 15 is positioned between the inner surface 13 of the striking face 11 and the club head enclosure 14. The insert 15 extends around a perimeter of the inner surface of the striking face, and is formed from a shape memory alloy, as described and discussed above. As best seen in FIGURE 2, the insert made of shape memory alloy is in effect sandwiched between the striking face 11 and the rear perimeter body 34 of the club head enclosure 14. As best seen in FIGURE 2, the insert 15 tapers in a longitudinal direction, to aid in assembly of the club. It will also be noted that the SMA insert is in direct contact with the inner surface 13 of the striking face, thereby facilitating the dampening of vibration and transfer of energy when the outer surface of the striking face contacts a golf ball. The insert 15 may be formed in various manners. In a first embodiment, the insert 15 is provided with a groove 16 extending into the insert from an inner surface 17 of the insert. The groove may have various cross-sectional shapes, for example, square, v-shaped and u-shaped, among others. The radius, angle, width and depth of the groove may be varied, depending on the design of the club head in which it is inserted. As illustrated in FIGURE 4, the insert 15 may also be solid.
Alternatively, as illustrated in FIGURE 5, the insert is formed from a length of shape memory alloy hollow tubing 18. Alternatively, a length of solid SMA wire may be positioned around the perimeter of the inner surface of the striking face. The length of SMA hollow tubing or solid rod can also be segmented to partially surround the perimeter of the inner surface. Again, the insert 15 is positioned against the inner surface of the striking face.
The insert 15 may also have a selected depth. For example, as illustrated in FIGURES 1 and 4, the insert 15 may have a sufficient depth such that an outer edge 19 of the insert 15 is co-extensive with an outer edge 20 of the striking face 11. Alternatively, the insert may have a smaller depth as illustrated in FIGURES 5 and 6, and may have a selected cross section. For example, the insert 15 has a substantially square cross section as illustrated in FIGURE 6, and a substantially triangular cross section, as illustrated in FIGURE 7. Although different depths and cross sections have been described herein for purposes of illustration, the insert may have any selected depth and cross section, e.g., V-shaped, elliptical and semicircular.
It will also be understood that the aspects of the invention described herein are equally applicable to any shape and size golf club. For example, the insert 15 may be positioned within a golf club 35 having a large club head enclosure, commonly referred to as a "wood," as illustrated in FIGURE 3.
In an alternative embodiment of the present invention, as illustrated in FIGURES 8 and 9, the club head enclosure 14 includes an inner region 21 that defines a perimeter adjacent the inner surface 13 of the striking face 11. A plurality of inserts formed from a shape memory alloy are provided in the inner region 21 of the club head enclosure, along the perimeter. The inserts may be of varying geometry, size, and spacing, and may be solid or hollow. For example, as illustrated in FIGURE 8, the inserts 22 are substantially cylindrical. In an alternative embodiment, as shown in FIGURE 9, the inserts 23 are substantially rectangular. In an alternative embodiment illustrated in FIGURE 10, the striking face 11 is made of a shape memory alloy, as discussed and described previously. Although a variety of SMAs may be used, in a preferred embodiment, the striking face 11 is made of Nitinol. Although the rear perimeter body 34 of the club head enclosure 14 may be flush against the inner surface of the SMA striking face, as illustrated in FIGURES 10 and 11, alternative configurations are provided in accordance with the present invention. For example, as illustrated in FIGURE 12, an inner region 24 of the club head enclosure 14 is formed into a force loading edge 25 which defines a perimeter adjacent the inner surface and that is in contact with the inner surface of the striking face. As illustrated in FIGURE 13, this inner region 24 of the club head enclosure may be formed from a shape memory alloy and supported by a rear perimeter body 34 coupled to the inner region 24 with connecting pins 36. Rear perimeter body 34 provides stiffness to the golf club head, to selectively minimize deflection. The edge 25 acts to concentrate impact forces against the face, thereby facilitating the phase transformation of the SMA. As a result, energy transfer to the ball by the striking face is increased, thereby increasing the distance the ball travels when hit.
As an alternative to an edge formed in a rear perimeter body 34 of the club head enclosure, the force loading edge 27 is provided on an insert 28 positioned within the club head enclosure 14, as illustrated in FIGURE 14. Although the force loading edge may have any selected cross section, in a preferred embodiment, it has a triangular cross section. As best seen in FIGURE 15, the force loading edge 27 is in direct contact with the striking face 11 made of SMA.
As an alternative to a force loading edge, a plurality of force loading point members 26 are coupled to the club head enclosure 14 via point supports 39 and positioned to contact the inner surface 13 of striking face 11, as seen in FIGURES 16 and 17. Alternatively, the force loading point members 26 are cylindrical members having a frustoconical tip positioned against the inner surface of the SMA striking face, as illustrated in FIGURE 18.
The force loading points or edges are preferably formed from a rigid and hard material such as metal, ceramic, diamond, or metal matrix composite. The force loading point support is preferably a rigid material made of metal, carbon composite, or metal matrix composite. To reduce cost and weight, the force loading point or edge support is preferably made of metal or carbon composite.
As an alternative to the striking face being formed of solid SMA, the striking face 11 may be formed of a plurality of SMA wires 29 formed integrally with another material such as a metal, polymer and composite, for example, metal matrix composite, polymer matrix composite, or ceramic matrix composite. As an alternative to a plurality of SMA wires, a plurality of lengths of SMA hollow tubing may be formed in a metal, polymer, and composite striking face. Depending on the particular club, the number of shape memory alloy elements, as well as the spacing, diameter, and angle in the metal, polymer, and composite may be varied to achieve selected results.
In an alternative embodiment, as illustrated in FIGURES 20-23, the golf club head 10 includes a striking face 11, a club head enclosure 14, and at least one insert made of shape memory alloy and coupled to the inner surface 13 of the striking face. Although the SMA insert may take various forms and orientations, in a preferred embodiment, a plurality of SMA rods or bars 30 extend across the inner surface of the striking face, the SMA wires being coupled to the club head enclosure 14. The SMA wires may be oriented substantially horizontally, as illustrated in FIGURE 20, or substantially vertically, as illustrated in FIGURE 21. As an alternative to SMA rods or bars, SMA hollow tubing may be used Again, the number of SMA rods, bars or hollow tubes, the spacing and angular orientation and diameter may be varied, depending on the relevant club design.
Alternatively, at least one or more pieces of SMA are attached directly to the inner surface of the striking face, as illustrated in FIGURES 22 and 23. As seen in FIGURE 23, a second insert or piece 32 of SMA may be coupled to an inner surface of a first piece 31 of SMA, which in turn is coupled to the inner surface of the striking face. Again, depending on the head design, the pieces or medallions of SMA may have various configurations, sizes, and thickness, depending on the desired results. Alternatively, the inserts may be formed from braided or woven SMA mesh, or may comprise a thin sheet or film of SMA.
Portions of the golf club head not formed of SMA may be made of any conventional material, for example, metal, a polymer (thermoplastic or thermosetting), ceramic, metal matrix composite (metallic matrix with metal, ceramic, carbon, graphite, glass, or polymeric fiber reinforcement), a polymer matrix (thermoplastic or thermosetting) composite (with metal, ceramic, carbon, graphite, glass, or polymeric fiber reinforcement), or a ceramic matrix composite (ceramic matrix with metal, ceramic, carbon, graphite, glass, or polymeric fiber reinforcement). Such other material would preferably contact the SMA by being alloyed, bonded, laminated, physically mixed, molded, or processed (such as in a metal, polymer or ceramic matrix composite) with the shape memory alloy. The shape memory alloy would preferably consist of, but not be limited, to the following physical forms: discrete particles; wire or fiber forms; sheet or film forms; small, hollow tubing of various cross-sectional geometries; and woven or braided forms made from the wire or fiber forms.
In operation, a golf club head provided in accordance with the present invention has the ability to dampen vibrational energy created upon impact with the ball due to the highly efficient damping capability of the SMA present in the head's construction. The damping capability is achieved by the stress-induced phase transformation of the alloy upon ball impact. Alternatively, the SMA may be selected and subjected to a heat processing treatment such that it is in the martensitic phase at a desired range of temperatures, in which it is believed the device will be used. As a result, the elements made of SMA exhibit superelastic properties when used in the selected range of temperatures, regardless of whether they are subjected to stress, for example, that generated by ball impact The use of an SMA that is in an initial martensitic phase is particularly appropriate in applications where the SMA element is not in direct contact with the inner surface of the club head, for example, as illustrated in FIGURE 8, or in those cases where a thickness of the SMA element makes it unlikely to flex The use of an SMA has the ability to dampen vibrational energy up to 20 times more efficiently than elastomeric materials per equivalent volumes.
In addition, the SMA performs work during strain recovery during unloading of the stress created at ball impact More particularly, the impact stress of the ball striking the SMA face of the club induces a solid-solid, reversible, diffusionless transformation in the SMA from the relatively stiffer austenitic phase to the relatively ductile, superelastic martensitic phase This property affects reversible strain (deflection) of the club head face As the stress is relieved upon the SMA striking face of the club head during rebound of the ball, the superelastic phase (martensitic) is transformed reversibly to the original, stiffer phase (austenitic) of the alloy. By concentrating the impact force of the ball onto small areas on the inner surface of the SMA striking face, through use of force loading points or edges, a threshold stress is reached which facilitates the phase transformation This unique property imparts additional efficiency of energy transferred to the ball at impact, thereby enhancing performance of the club head by increasing ball distance Therefore, the use of SMA in the club head provides the dual benefits of imparting a desired "feel" to the user as well as increasing the performance of the club head
A golf club head having improved energy transfer and vibration dampening properties has been shown and described. From the foregoing, it will be appreciated that although embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit of the invention Thus, the present invention is not limited to the embodiments described herein but rather is defined by the claims which follow