Golf club shaft

Abstract

A golf club shaft having an exterior with a non-circular cross-section along at least a portion of its length is disclosed. In one embodiment, the cross-section of the exterior of the shaft along an intermediate portion of the shaft between the butt end and the tip end is non-circular. In this embodiment, the cross-section of the exterior of the shaft at the end regions containing the butt and tip ends of the shaft may be circular. The cross-section of the intermediate portion may be any suitable shape, such as a symmetrical shape. In one version of such an embodiment, the cross-section of the exterior of the shaft along an intermediate portion of the shaft is substantially triangular in configuration.

Description

FIELD OF THE INVENTION

This invention relates to golf clubs, more particularly to golf club shafts. More particularly still, this invention relates to golf club shafts having a non-circular exterior cross-section along at least a portion of their length.

BACKGROUND OF THE INVENTION

Currently, golf club shafts are hollow steel or graphite tubes that have a relatively thick outside dimension at the grip end of the golf club, that narrows as the club head is approached. Some golf club shafts, particularly those made of steel, may have a series of steps therein. In these shafts, the thickness of the shafts changes to a narrower thickness at each step from the grip end to the tip end. Other golf club shafts taper smoothly from the grip end to the tip end. Still other golf club shafts, such as the TAYLOR MADE® Bubble™ shaft described in U.S. Pat. No. 5,316,299 issued to Feche, et al. on May 31, 1994, have had discontinuities in thickness, such as a bubble, between their butt end and tip end.

Golf club shafts must meet the requirements of the United States Golf Association Rules of Golf (“Rules of Golf”) to be considered “legal” for tournament play. The USGA Rules require in Appendix II, Rule 4-1b, that the shaft be so designed and manufactured that at any point along its length:

• • (i) it bends in such a way that the deflection is the same regardless of how the shaft is rotated about its longitudinal axis; and
  • (ii) it twists the same amount in both directions.

This Rule is believed to be the reason that most golf club shafts are currently of circular cross-section. Over the years, golf club shafts have been proposed with various other cross-sections. One example of such a shaft is described in U.S. Pat. No. 5,545,094 issued to Hsu. Most of these proposed shafts are not believed to have been marketed on a commercial scale in the U.S. One possible reason for this may be that they have not received U.S.G.A. approval. Whether the shaft described in the Hsu reference has been approved, however, is not known.

SUMMARY OF THE INVENTION

The present invention relates to golf club shafts having an exterior with a non-circular cross-section along at least a portion of the length of the shaft.

There are numerous, non-limiting embodiments of the invention. All embodiments, even if they are only described as being “embodiments” of the invention, are intended to be non-limiting (that is, there may be other embodiments in addition to these), unless they are expressly described as limiting the scope of the invention.

The golf club shaft has a longitudinal axis, a cross-section, a butt end, a tip end, and a length extending from the butt end to the tip end. In one non-limiting embodiment, the cross-section of the exterior of the shaft along an intermediate portion of the shaft between the butt end and the tip end is non-circular. In this embodiment, the cross-section of the exterior of the shaft at the end regions containing the butt and tip ends of the shaft may be circular. The cross-section of the intermediate portion may be any symmetrical shape. In one version of such an embodiment, the cross-section of the exterior of the shaft along an intermediate portion of the shaft is substantially triangular in configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the invention will be better understood from the following description taken in conjunction with the accompanying drawings (some of which have been enlarged).

FIG. 1 is a perspective view of a golf club comprising one embodiment of the golf club shaft of the present invention.

FIG. 2 is one possible end view of the golf club shaft at the butt end of the shaft.

FIG. 3 is one possible end view of the golf club shaft at the tip end of the shaft.

FIG. 4 is one possible cross-sectional view of the golf club shaft taken along line 4-4 of FIG. 1.

FIG. 5 is a cross-sectional view of another embodiment of the golf club shaft taken along line 4-4 of FIG. 1.

FIG. 6 is a cross-sectional view of another embodiment of the golf club shaft taken along line 4-4 of FIG. 1.

FIG. 7 is a partially fragmented, enlarged perspective view of one embodiment of the golf club shaft of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of a golf club 20 that is provided with one non-limiting embodiment of the golf club shaft of the present invention.

The golf club 20 has a shaft 22, a grip 24, and a club head 26. The shaft 22 runs from the grip end (“upper end”) 20A of the club to the club head end (“lower end”) 20B. The end of the shaft 22 at the upper end 20A of the club is referred to as the “butt” 22A of the shaft. The end of the shaft 22 at the lower end 20B of the club is referred to as the “tip” 22B of the shaft. The club head 26 has a club face 28 for striking the ball, a back 30 on the opposite side of the club head, a sole 31, and a hosel 32 (which may be optional) where the tip 22B of the shaft 22 is inserted into the club head 26. The golf club shaft 22 has a leading edge 34 that is on the half of the shaft aligned with the face 28 of the golf club. The shaft 22 has a trailing edge 36 on the half of the shaft aligned with the back of the club head 30.

The golf club shaft 22 may be of any suitable length. Typical lengths of shafts range from about 40-41 inches (about 100-105 cm) for shafts designed to be installed in “iron” type golf clubs to about 46 inches (about 115-120 cm), or more, for shafts designed to be installed in “wood” type golf clubs.

The golf club shaft 22, along its length, comprises a first end portion (or first end region) 38 comprising the butt end 22A of the shaft, a second end portion (or second end region) 42 comprising the tip end 22B of the shaft, and an intermediate portion (or intermediate region) 40 between said first and second end portions 38 and 42. These three portions of the shaft 22 may be any suitable length. That is, they may comprise any suitable portion of the overall length of the shaft. The different portions of the shaft 22 may each comprise any suitable percentage of the overall length of the shaft including, but not limited to about: 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, 90%, or 95%, or any range extending from one of these percentages to another of these percentages. For example, in one embodiment, the three portions of the shaft 22 may each comprise about ⅓ the overall length of the shaft 22. In other embodiments, one portion of the shaft 22 may comprise less than or equal to about ¼ the overall length of the shaft 22, and the two remaining portions may comprise the remaining ¾ of the length of the shaft (e.g., one of the remaining portions could comprise about ¼ of the overall length of the shaft 22, and the other portion remaining could comprise about ½ the overall length of the shaft 22). Other relationships between the lengths of the different portions of the shaft 22 are also possible.

The first end portion 38 of the shaft 22 may, for example, extend downward from the butt end 22A of the shaft any suitable distance toward the tip 22B of the shaft. In one embodiment, the first end portion 38 may extend downward to the place where the shaft 22 emerges from the grip 24. Golf club grips 24 are typically about 10-11 inches (about 25-28 cm) long. In other embodiments, the first end portion 38 may extend downward beyond the location where the shaft 22 emerges from the grip 24. It should be understood that the brackets designating the three regions of the shaft are for convenience only, and represent just one possible embodiment, and the three portions of the shaft 22 are not limited to the exact dimensions delineated by the brackets in FIG. 1.

The intermediate portion 40 may, for example, extend from the location where the grip 24 begins (the lowermost portion of the grip 24) to the location where the shaft 22 is inserted into the hosel 32 or the club head 26. This region of the shaft may be referred to herein as the “exposed portion” of the shaft 22. In other embodiments, as shown, for example, by the inner set of brackets 40′ in FIG. 1, the intermediate portion may comprise less of the overall length of the shaft than the exposed portion of the shaft. When the intermediate portion 40 of the shaft comprises less of the overall length of the exposed portion of the shaft, it may comprise any suitable percentage of the overall length of the exposed portion of the shaft including, but not limited to about: 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, 90%, or 95%, or any range extending from one of these percentages to another of these percentages. In still other embodiments, the intermediate portion 40 of the shaft 22 may comprise a larger portion of the shaft 22 than the exposed portion of the shaft 22. In these latter embodiments, some of the intermediate portion 40 of the shaft may lie underneath the grip 24 and/or within the hosel 32 or club head 26.

The intermediate portion 40 of the shaft may be centered relative to either the overall length of the shaft, or relative to the exposed portion of the shaft 22. In other embodiments, however, the intermediate portion 40 of the shaft 22 need not be centered in such a manner. The intermediate portion 40 of the shaft 22 may, for instance, be located closer to the butt 22A, or alternatively, closer to the tip 22B of the shaft 22. The shaft 22 has a mid-point, M, along its length between the butt 22A and tip 22B. The intermediate portion 40 of the shaft may be located entirely above the midpoint of the shaft 22, or entirely below the midpoint of the shaft 22. In other embodiments, a portion of the intermediate portion 40 of the shaft 22 may be located above the midpoint, M, of the shaft, and a portion of the intermediate portion 40 of the shaft 22 may be located below the midpoint, M, of the shaft. In some embodiments, the intermediate portion 40 of the shaft may either be located substantially above the midpoint, M, of the shaft 22, or substantially below the midpoint, M, of the shaft 22. In some embodiments, the intermediate portion 40 of the shaft 22 may be located within the upper ⅓ of the shaft, the lower ⅓ of the shaft, or the middle ⅓ of the shaft.

The second end portion 42 of the shaft 22 may, for example, extend upward from the tip 22B of the shaft any suitable distance toward the butt end 22A of the shaft. In one embodiment, the second end portion 42 may extend upward from the tip 22B of the shaft to the uppermost portion of the hosel 32. In other embodiments, the second end portion 42 may extend upward beyond the uppermost portion of the hosel 32 (or to the place where the shaft emerges from the club head 26, if there is no hosel 32).

The different portions of the shaft 22 may have any suitable cross-sectional configuration. As shown in FIG. 2, in the embodiment shown in FIGS. 1-5, the cross-section of the exterior of the shaft 22 along at least a portion of the length of the first end portion 38 of the shaft 22 (containing the butt 22A of the shaft) may be circular. This allows the shaft 22 to fit inside conventional grips 24. The cross section of the grip 24 must be circular to conform to USGA Rules. As shown in FIG. 3, in this embodiment, the cross-section of the exterior of the shaft 22 along at least a portion of the length of the second end portion 42 of the shaft 22 (containing the tip 22B of the shaft) may also be circular. This allows the tip end 22B of the shaft 22 to fit into conventional club head hosels 32, or other openings in the club head for receiving a shaft.

The cross-section of the exterior of the shaft 22 in one or both of the first end portion 38 and second end portion 42 may be circular along any suitable portion of the length of such portions, including the entire length of such portions, or substantially the entire length of such portions. However, it should be understood that it is within the scope of the present invention for one or more sections along the length of the first end portion 38 or second end portion 42 to have a cross-section that is non-circular.

In this embodiment, however, as shown in FIG. 4, the cross-section of the exterior of the shaft 22 along at least a portion of the length of the intermediate portion 40 of the shaft 22 is non-circular. The cross-section of the exterior of the shaft 22 in the intermediate portion 40 may be non-circular along any suitable portion of the length of the intermediate portion 40, including the entire length of the intermediate portion 40, or substantially the entire length of the intermediate portion 40. It should be understood, however, that it is within the scope of the present invention for one or more sections along the length of the intermediate portion 40 to have a cross-section that is circular. In the embodiment shown in FIG. 4, the shaft 22 is substantially hollow. As shown in FIG. 4, the shaft 22 has an interior surface 44 and an exterior surface 46.

The exterior surface 46 of the intermediate portion 40 may have any suitable non-circular cross-sectional shape along at least a portion of the length thereof. Suitable shapes include symmetrical shapes. The golf club shaft 22 may, for example, have an intermediate portion 40 with an exterior 46 cross-sectional configuration of a regular polygon, or a modified regular polygon shape. In certain embodiments, the exterior configuration of the intermediate portion 40 of the shaft 22 may be substantially, or entirely: a triangular, square, pentagonal, hexagonal, septagonal, octagonal, or other polygon with any other number of sides). In other embodiments, the exterior configuration of the shaft 22 may not include configurations in which the cross-sectional configuration is one or more of the foregoing shapes. In the particular embodiment shown, the cross-section of the exterior 46 of the shaft 22 along the intermediate portion 40 of the shaft 22 is substantially triangular in configuration.

The portion of the golf club shaft 22 at this particular cross-section has an exterior cross-section that is substantially in the configuration of an equilateral triangle. The cross-section of the shaft has three sides 48, and three corners 50. The cross-section of the shaft 22 shown in FIG. 4 is symmetrical about the longitudinal axis, L. A shaft having the cross-section of a regular polygon (all sides being substantially the same length) is believed to have the same bending properties regardless of how the shaft is rotated about its longitudinal axis, L, even when the shaft 22 is bent at locations corresponding to the corners 50.

The substantially triangular shape of the cross-section of the shaft 22 may be exactly in the shape of a triangle, with straight side edges 48. However, in the embodiment shown, the cross-section is in a modified triangular-shaped configuration. In the embodiment shown in FIG. 4, the sides 48 of the modified triangular-shaped cross-section are convex outwardly curved, and the corners 50 of the modified triangular-shaped cross-section are rounded. The cross-section of the shaft 22 can, thus, be formed by rectilinear segments, curvilinear segments, or both. The other polygon-shaped structures described herein can also be similarly modified. In other embodiments, the sides and/or the corners of the polygon can have larger or smaller radii of curvature than that shown in the drawings. In still other embodiments, the sides of the polygon (or even the corners thereof), instead of being convexly curved, may be concavely curved.

The cross-section of the interior surface 44 of the intermediate portion 40 of the shaft 22 can be circular as shown in FIG. 4. In other embodiments, however, as shown in FIG. 5, the cross-section of the interior surface 44 of the intermediate portion 40 of the shaft 22 can have a non-circular configuration. For instance, as shown in FIG. 5, the cross-section of the interior surface 44 of the intermediate portion 40 of the shaft 22 has a similar configuration to the cross-section of the exterior surface 46 of the shaft. Thus, in the embodiment shown in FIG. 5, both the interior surface 44 and exterior surface 46 of the intermediate portion 40 of the shaft 22 may have a substantially triangular configuration.

The shaft 22 has side walls 52 between the interior and exterior surfaces 44 and 46. The side walls 52 can be uniform, or non-uniform in width, or thickness, around the cross-section of the shaft. For example, the side walls 52 may be substantially uniform in thickness in the embodiment shown in FIG. 5 where both the interior surface 44 and exterior surface 46 of the intermediate portion 40 of the shaft 22 have a substantially triangular configuration. The side walls 52 of the intermediate portion of the shaft 22 may have a non-uniform thickness in embodiments such as the one shown in FIG. 4 where the cross-section of the interior surface 44 of the intermediate portion 40 of the shaft 22 is circular.

FIG. 6 shows an alternative embodiment in which the shaft 22 comprises a two component structure. In the two component structure shown in FIG. 6, the shaft 22 comprises an inner component 54, such as a component having a circular cross-section, and an outer component 56 having an exterior surface that provides the shaft with the desired non-circular cross-section. In one version of such a two component structure, the inner component 54 may comprise a shaft having a circular cross-section. The inner shaft component 54 in some embodiments, may be made of steel, graphite, or some other suitable material, and the outer component 56 may be a flexible material joined thereto.

The term “joined”, as used herein, encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e., one element is essentially part of the other element. The term “joined” includes both those configurations in which an element is temporarily joined to another element, or in which an element is permanently joined to another element.

In the two component structure shown in FIG. 6, the inner component 54 has an inner surface and an outer surface, and both the inner surface and the outer surface have a circular cross-section. In addition to being flexible, the outer component 56 may also be compressible and/or resilient. In still other embodiments, however, the outer component 56 need not be compressible or resilient. This two component structure can form any suitable portion(s) of the shaft 22, including one or both of the end portions 38 and 42 of the shaft 22, or the intermediate portion 40 of the shaft 22.

In other embodiments, as shown in FIGS. 2-5, it may be desirable for the shaft 22 to comprise a single component structure in which there are no separate inner and outer components. This may be desirable for any suitable reason. Such a structure may, for instance, be desirable: from a manufacturing standpoint (that is, to simplify manufacturing); to facilitate U.S.G.A. approval; or, for any other purpose.

The different portions of the shaft 22 (first end portion 38, intermediate portion 40, and second end portion 42) can have any suitable interior dimensions. It is, therefore, not necessary for the interior dimensions of the different portions of the shaft 22 (first end portion 38, intermediate portion 40, and second end portion 42) to be equal since shafts typically taper from a larger exterior dimension to a smaller dimension from the butt 22A of the shaft to the tip 22B of the shaft 22. Thus, it may be desirable for the interior dimension (or the “inside diameter” for a cylindrical portion) of the shaft 22 to be smaller at the tip 22B than at the butt 22A of the shaft 22. In addition, it may be desirable for the thickness of the walls 52 of the shaft 22 to be larger at the tip 22B than at the butt 22A of the shaft, particularly in the case of shafts made of graphite. This may be done to provide the shaft with greater strength at the tip 22B end.

The different portions of the shaft 22 (first end portion 38, intermediate portion 40, and second end portion 42) can have any suitable exterior dimensions. It is desirable for the first end portion 38 of the shaft 22 to have an exterior configuration and dimensions that make it is capable of fitting into a conventional grip 24. Examples of suitable exterior dimensions for the butt 22A of the shaft 22 include an outside diameter (or “OD”) of about 0.6 inches, 0.625 inches, 0.63 inches, and 0.635 inches (about 1.5 cm, 1.59 cm, 1.6 cm, and 1.61 cm). It is desirable for the second end portion 42 of the shaft 22 to have an exterior configuration and dimensions that make it is capable of fitting into the hosel 32, or other opening in a club head 26 for receiving a shaft. Examples of suitable exterior dimensions for the tip 22B of the shaft include an outside diameter of about: 0.335 inches, 0.35 inches, and 0.37 inches (about 0.85 cm, 0.9 cm, and 0.94 cm). The exterior dimensions of the shaft 22 may generally decrease within any one or more portions of the shaft 22 from the butt 22A of the shaft to the tip 22B of the shaft 22.

The exterior dimensions of the intermediate portion 40 of the shaft 22 may be of a size that is between the exterior dimensions of the first end portion 38 and second end portion 42 of the shaft 22. However, the exterior dimensions of the intermediate portion 40 of the shaft 22 are not limited to those that are of a size that is between the exterior dimensions of the first end portion 38 and second end portion 42 of the shaft 22. For example, it is possible for one or more portions of the intermediate portion 40 of the shaft 22 to be larger than the exterior dimension of a portion of the first end portion 38 of the shaft. It is possible for one or more portions of the intermediate portion 40 of the shaft 22 to be smaller than the exterior dimension of a portion of the second end portion 42 of the shaft. The shaft 22 may, or may not, be constructed so that any variations in the cross section of the shaft 22 are gradual so that there is a smooth transition along the shaft between such different cross-sections. In addition, the shaft 22 can be provided with a series of tapering steps similar to ones found in conventional cylindrical steel golf club shafts.

There are also transition portions (or “transition regions”) 58 and 60 between the different portions of the shaft 22 where the exterior shape of the shaft changes from one cross-sectional shape to a different cross-sectional shape. FIG. 7 shows one non-limiting embodiment of a shaft with transition regions 58 and 60. (The interior of the shaft 22 is shown in dashed lines in FIG. 7 because it can have any suitable configuration.) As shown in FIG. 7, the first transition portion (or “first transition region”) 58 is at the location where the circular configuration of the first end portion 38 of the shaft 22 changes to the substantially triangular configuration of the intermediate portion 40. The second transition portion (or “second transition region”) 60 is at the location where a substantially triangular configuration of the intermediate portion 40 of the shaft 22 changes to the circular cross-sectional configuration of the second end portion 42. These transition portions may be considered to comprise portions of the shaft 22 that are separate from the first end portion 38, intermediate portion 40, and second end portion 42, or they may be considered to comprise part of the three main portions of the shaft 22. The transition portions may also be considered to comprise portions of the shaft where one portion of the shaft merges into another portion of the shaft 22.

The transition portions 58 and 60 can have any suitable configuration. In the case of the embodiment shown in the drawings which has an intermediate portion 40 with a substantially triangular cross-section, the first transition portion 58 comprises a portion of the shaft 22 in which the cross-section has a radius of curvature that decreases at three locations (or “places”) 62 disposed on the exterior surface 46 of the shaft 22 from the first end portion 38 toward the intermediate portion 40. These three locations 62 are disposed approximately equal distances from each other around the perimeter of the exterior surface 46 of the shaft 22. If the cross-section of the shaft is looked at in geometric terms, these three locations may be disposed radially outward from the longitudinal axis, L, of the shaft at points that are approximately 120° apart around the perimeter of the exterior surface 46 of the shaft 22. The portions 64 of the perimeter of the exterior surface 46 of the shaft 22 that lie between the aforementioned three locations 62 have a radius of curvature that increases as the shaft 22 transitions from the first end portion 38 to the intermediate portion 40.

The second transition portion 60 comprises a portion of the shaft 22 in which the cross-section has a radius of curvature that increases at three locations (or “places”) 66 disposed on the exterior surface 46 of the shaft 22 from the intermediate portion 40 toward the second end portion 42. These three locations 66 are disposed approximately equal distances from each other around the perimeter of the exterior surface 46 of the shaft 22. These three locations 66 may be disposed radially outward from the longitudinal axis, L, of the shaft at points that are approximately 120° apart around the perimeter of the exterior surface 46 of the shaft 22. The portions 68 of the perimeter of the exterior surface 46 of the shaft 22 that lie between the aforementioned three locations 66 have a radius of curvature that decreases as the shaft 22 transitions from the intermediate portion 40 to the second end portion 42.

The transition portions 58 and 60 can be relatively smooth, or more sharp or abrupt. The transition portions 58 and 60 may have any suitable length. Suitable lengths include, but are not limited to: less than or equal to about 0.5 inch, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, . . . (etc.) inches (about 1.3, 2.5, 5, 7.5, 10, 12.5, 15, 18, 20, 23, 25.4, 28, 30, . . . cm). Typically, the longer transition portions will be smoother. For example, a relatively smooth transition portion may be considered to be one that has a length greater than or equal to about any of the following: 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, . . . (etc.) inches. A relatively abrupt transition portion may be considered to be one that has a length of less than or equal to any of the above amounts. In some embodiments of the shaft 22, the first and second transition portions 58 and 60 may both either be relatively smooth, or relatively abrupt. In other embodiments of the shaft 22, one of the transition portions may be relatively smooth, and one may be relatively abrupt, or at least more abrupt than the relatively smooth transition portion.

The cross-section of the shaft 22 can be aligned in any suitable orientation in the club 20 to form the leading 34 and trailing edges 36 of the shaft. In certain embodiments, it may be desirable for one of the corners 50 of such a triangular, or modified-triangle structure (or other polygon-shaped structure) to be aligned to form the leading edge 34 of the shaft 22. In other embodiments, it may be desirable for one of the sides 48 of such a triangular, or modified-triangle structure (or other polygon-shaped structure) to be aligned to form the leading edge 34 of the shaft 22.

FIG. 4 shows that when one of the corners 50 is aligned to form the leading edge 34 of the shaft 22, there are several different ways that the corner 50 can be positioned, and still form the leading edge 34. As shown in FIG. 4, there are at least three axes, A1, A2, and A3, which can represent a plane that divides the shaft 22 into a leading half and a trailing half, which may be oriented to permit the corner labeled with reference number 50 to form the leading edge 34 of the shaft.

For example, if the shaft 22 in FIG. 4 is oriented so that axis A1 divides the shaft 22 into a leading half and a trailing half, the corner labeled with reference number 50 will form the leading edge 34 of the shaft. However, this corner 50 will be oriented on the bottom portion of the shaft when the club is viewed from the position shown in FIG. 1. In embodiments in which the shaft 22 is oriented so that axis A3 divides the shaft 22 into a leading half and a trailing half, the corner labeled with reference number 50 will form the leading edge 34 of the shaft. However, this corner 50 will be oriented on the top portion of the shaft when the club is viewed from the position shown in FIG. 1. In embodiments in which the shaft 22 is oriented so that axis A2 divides the shaft 22 into a leading half and a trailing half, the corner labeled with reference number 50 will form the leading edge 34 of the shaft. However, this corner 50 will be oriented midway between the top and the bottom portion of the shaft when the club is viewed from the position shown in FIG. 1. The cross-sections of the intermediate portion 40 of the shaft 22 in FIGS. 3 and 5-6 may also be oriented in any of the manners specified.

The golf club shaft 22 can be made of any suitable material or materials. The golf club shaft 22 can be made of a single material, or it can be made of more than one material. Suitable materials include, but are not limited to steel, graphite, aluminum, titanium, fiber reinforced plastic, or any other material known in the art for making golf club shafts. The shaft 22 can also be made of composites or combinations of any of these materials.

The shaft 22, or any portion thereof, may be made of one or more (or even multiple) layers of the same or different material. For instance, the shaft 22 can be made of multiple layers of graphite that are formed into a tube. In some embodiments, such multiple layers can be formed into the shaft 22 so that discrete layers remain visible as a laminate or layered structure to the unaided eye (that is, macroscopically). In other embodiments, the multiple layers may be formed or molded, by heating or other methods, into a composite structure in which the discrete layers are not visible to the unaided eye after the shaft has been formed.

In certain embodiments, it may be desirable for the materials comprising the shaft 22 to be elastic and/or compressible. However, in other embodiments, it may be desirable for the materials comprising the shaft 22 to be substantially non-elastic and/or substantially non-compressible when the shaft is in its finished form. In some embodiments, it may be desirable for the materials comprising the shaft to exclude viscoelastic foam material.

The first end portion 38, intermediate portion 40, and second end portion 42 can be made from the same material(s), or different materials. In the embodiments shown in FIGS. 1-5, the first end portion 38, intermediate portion 40, and second end portion 42 are made from the same material(s). These same materials may be in the form of a single material or a composite structure when the shaft 22 is in its finished form. In other embodiments, instead of comprising a single material or a composite structure, one or more of the first end portion 38, intermediate portion 40, and second end portion 42 can comprise any of the other types of structures described herein. The shaft 22 can comprise any possible combination of the various materials or structures described herein as any one or more of its first end portion 38, intermediate portion 40, and second end portion 42.

The different portions of the shaft, first end portion 38, intermediate portion 40, and second end portion 42, can be comprised of a single continuous piece, or they can comprise two or more segments. If the shaft 22 comprises two or more segments, the segments can be joined together generally end-to-end, or in a partially overlapping end-to-end configuration. An example of a partially overlapping end-to-end configuration would be a shaft comprising at least two segments where the end of one segment fits into the end of another segment.

Numerous other embodiments are possible. For example, in other embodiments, the shaft 22 need only have two regions with different cross-sections. For instance, the shaft 22 may only have a first end portion, and the intermediate portion can also comprise the second end portion and extend all the way to the tip 22B of the shaft 22. In other embodiments, the shaft 22 may have more than three regions with different cross-sections. In these, or other embodiments, the interior of the shaft 22 may be non-hollow. That is, the interior of the shaft 22 may be filled, at least partially, or entirely with some substance or structure. The golf club and shaft can also be provided with any of the features described in, or be constructed in accordance with the disclosures of: U.S. Pat. No. 5,316,299 issued to Feche, et al.; U.S. Pat. No. 6,561,992 B2 issued to Bamber; and, U.S. Pat. D-505,986 S issued to Bamber.

The golf club shaft 22 described herein can provide one or more advantages. It should be understood, however, that the golf club shaft 22 is not required to provide any advantages unless they are specifically set forth in any of the appended claims. In addition, it should be understood that the benefits described herein are prophetic, and remain to be proven by testing. The cross-sectional shape of the intermediate portion 40 of the shaft may, for example, be used to reduce drag on the shaft, to bring the golfer's swing into impact on a certain swing path, or both. The cross-sectional shape of the intermediate portion 40 may serve to assist the golfer in moving the club into the impact zone by squaring the clubface. The shaft 22 may allow the golf club to be swung faster by the player with the same or less effort to create more power, and longer shots, straighter shots (that is, it may minimize shot dispersion), or both. It is believed that the golf club shaft will conform to the Rules of Golf. The golf club shaft 22 is believed to bend in such a way that the deflection is the same regardless of how the shaft is rotated about its longitudinal axis; and twist the same amount in both directions even though it has an intermediate portion with a non-circular cross-section.

The golf club shaft 22 can be made in any suitable manner. Methods of making golf club shafts are well known. Any suitable method can be modified to produce the golf club shaft described herein. Some non-limiting embodiments of methods for making golf club shafts are described in: U.S. Pat. Nos. 6,171,696 B1 and 6,273,830 B1 issued to Takemura, et al., and U.S. Pat. No. 6,857,972 B2 issued to Kumamoto. These methods, or other methods, can be modified by utilizing a mandrel having the configuration desired for the inner surface of the shaft, and forming the shaft around the mandrel by casting, molding, forging, or otherwise shaping the shaft material or materials. For example, in one embodiment of a method of making the shaft, the shaft is formed in a mold that is provided in the configuration of the exterior surface of the shaft. Other methods of providing a golf club shaft with a non-circular cross-section are described in U.S. Pat. No. 6,561,992 B2 issued to Bamber.

The disclosures of all patents and publications mentioned throughout this patent application are hereby incorporated by reference herein. It is expressly not admitted, however, that any of the documents incorporated by reference herein teach or disclose the present invention. It is also expressly not admitted that any of the commercially available materials or products described herein teach or disclose the present invention.

It should be understood that every maximum numerical limitation given throughout this specification includes every lower numerical limitation, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this specification includes every higher numerical limitation, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this specification includes every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.

While particular embodiments of the subject invention have been described, it will be obvious to those skilled in the art that various changes and modifications of the subject invention can be made without departing from the spirit and scope of the invention. In addition, while the present invention has been described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of the invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

Claims

1. A golf club shaft having a longitudinal axis, a cross-section, an exterior surface, a butt end, a tip end, a first end portion comprising said butt end, a second end portion comprising said tip end, and an intermediate portion between said first and second end portions, and a length extending from said butt end to said tip end, wherein at least part of said intermediate portion of said shaft has an exterior surface with a cross-section that is substantially triangular in configuration, wherein said substantially triangular cross-section has a periphery formed by three sides that meet at rounded corners, wherein each of said three sides has a substantially equal length, and the three sides are convex outwardly continuously around said periphery, and at least part of the length of said shaft in said first end portion has an exterior surface with a cross-section that is circular.

2. The golf club shaft of claim 1 wherein said three sides of said periphery of said substantially triangular cross-section have equal lengths.

3. The golf club shaft of claim 1 having an interior surface along at least a portion of its length, and being hollow inside at least a portion of said interior surface.

4. The golf club shaft of claim 3 wherein the cross-section of said portion of said interior surface is substantially circular.

5. The golf club shaft of claim 4 wherein said substantially circular cross-section of said portion of interior surface comprises at least part of the length of said intermediate portion.

6. The golf club shaft of claim 5 wherein the interior surface and exterior surface of the shaft, along said at least part of the length of said intermediate portion, define a wall therebetween, and the wall has portions with different thicknesses.

7. The golf club shaft of claim 6 wherein the wall is thicker in the regions of the corners than in the region adjacent the sides.

8. The golf club shaft of claim 3 comprising a macroscopically single layer structure.

9. The golf club shaft of claim 3 wherein said first end portion, said second end portion, and said intermediate portion of said shaft comprise the same structure and material.

10. A golf club shaft according to claim 1 further comprising a club head joined to the second end portion of said shaft and a grip joined to the first end portion of said shaft to form a golf club.

11. A golf club shaft having a longitudinal axis, an exterior surface, a cross-section, a butt end, a tip end, and a length extending from said butt end to said tip end, said golf club shaft comprising: (a) a first end portion comprising the butt end of the shaft wherein the cross-section of the exterior of said shaft along a portion of the length of said shaft extending from said butt end part of the distance toward said tip end is circular;(b) a second end portion comprising the tip end of the shaft, wherein the cross-section of the exterior of said shaft along a portion of the length of said shaft extending from said tip end part of the distance toward said butt end is circular; and(c) an intermediate portion between said first and second end portions, wherein the cross-section of the exterior surface of said shaft along at least part of the length of said intermediate portion is substantially triangular in configuration, wherein the substantially triangular cross-section has a periphery formed by three sides that meet at rounded corners, wherein each of said three sides has a substantially equal length, and said three sides are convex outwardly continuously around said periphery.

12. The golf club shaft of claim 11 having an interior surface along at least a portion of its length, and being hollow inside at least a portion of said interior surface.

13. The golf club shaft of claim 12 wherein the cross-section of said portion of said interior surface is substantially circular.

14. The golf club shaft of claim 11 wherein at least one of said first end portion and said second end portion merges into said intermediate portion in a transition region, wherein in said transition region the configuration of the exterior surface of said shaft changes from one configuration to a different configuration over a portion of the length of said shaft.

15. The golf club shaft of claim 14 wherein the exterior cross-section of the first end, second end, and intermediate portions of said shaft each have at least one radius of curvature, and said transition region is located where said first end portion merges into said intermediate portion, wherein said transition region comprises: (i) a portion of the shaft in which the cross-section has a radius of curvature at three spaced apart locations disposed on the exterior surface of the shaft, wherein the radius of curvature at said three locations decreases from the first end portion toward the intermediate portion; and(ii) three portions of the perimeter of the cross-section of exterior surface of the shaft that lie between the aforementioned three locations, wherein said three portions of the perimeter of the shaft have a radius of curvature that increases as the shaft transitions from the first end portion to the intermediate portion.

16. The golf club shaft of claim 14 wherein the exterior cross-section of the first end, second end, and intermediate portions of said shaft each have at least one radius of curvature, and said transition region is located where said intermediate portion merges into said second end portion, wherein said transition region comprises: (i) a portion of the shaft in which the cross-section has a radius of curvature at three spaced apart locations disposed on the exterior surface of the shaft, wherein the radius of curvature at said three locations increases as the shaft transitions from the intermediate portion to the second end portion; and(ii) three portions of the perimeter of the cross-section of exterior surface of the shaft that lie between the aforementioned three locations, wherein said three portions of the perimeter of the shaft have a radius of curvature that decreases as the shaft transitions from the intermediate portion to the second end portion.

17. The golf club shaft of claim 11 wherein said shaft, at any point along its length: (i) bends in such a way that the deflection is the same regardless of how the shaft is rotated about its longitudinal axis; and(ii) twists the same amount in both directions.

18. A golf club shaft according to claim 11 further comprising a club head joined to the second end portion of said shaft and a grip joined to the first end portion of said shaft to form a golf club.

19. A golf club shaft having a longitudinal axis, a cross-section, an exterior surface, a butt end, a tip end, a first end portion comprising said butt end, a second end portion comprising said tip end, and an intermediate portion between said first and second end portions, and a length extending from said butt end to said tip end, wherein at least part of said intermediate portion of said shaft has an exterior surface with a cross-section that is substantially triangular in configuration and has three convex sides that meet at rounded corners, wherein each of said three sides has a substantially equal length, and each side has a radius of greater than the maximum dimension of the shaft at the cross-section, and at least part of the length of said shaft in said first end portion has an exterior surface with a cross-section that is circular.