Shaft for Golf Club

This application is a continuation of U.S. patent application Ser. No. 17/562,905, filed on Dec. 27, 2021, which is a continuation-in-part of U.S. patent application Ser. No. 17/544,033, filed Dec. 7, 2021, the entirety of each of which is hereby incorporated by reference. To the extent appropriate, the present application claims priority to the above-reference applications.

During the game of golf, a golfer may often desire to hit a golf ball further. For instance, with a driver, the golfer may desire to hit the golf ball as far as possible. One factor in the distance the golf ball travels is the club head speed of the golf club as it is being swung. As a golf club is swung by a golfer, the golf club experiences significant drag effects that require greater power from the golfer to achieve higher swing speeds. Thus, a reduction in drag of the golf club head allows for higher club head speeds with the same amount of effort from the golfer.

It is with respect to these and other general considerations that the aspects disclosed herein have been made. Also, although relatively specific problems may be discussed, it should be understood that the examples should not be limited to solving the specific problems identified in the background or elsewhere in this disclosure.

Examples of the present disclosure describe improved golf clubs with improved properties that provide increased swing speeds.

According to an aspect, the technology relates to a shaft for a golf club, including a tip end configured to couple to a golf club head; a butt end opposite to the tip end; and a butt end portion that extends in a butt-to-tip direction from the butt end by at least 50 mm and has an average rate of change of bending stiffness in a tip-to-butt direction, wherein a greatest rate of change of bending stiffness of the shaft in the tip-to-butt direction is at least 2.7 times the average rate of change of bending stiffness of the butt end portion.

In some examples, the greatest rate of change of bending stiffness of the shaft in the tip-to-butt direction is at least 5.0 times the average rate of change of bending stiffness of the butt end portion.

In some examples, the greatest rate of change of bending stiffness of the shaft in the tip-to-butt direction is at least 10.0 times the average rate of change of bending stiffness of the butt end portion.

In some examples, the butt end portion extends in the butt-to-tip direction from the butt end by at least 150 mm.

In some examples, the shaft has a tip end portion extending in the tip-to-butt direction from the tip end by at least 150 mm, and a ratio of the average bending stiffness of the butt end portion to the average bending stiffness of the tip end portion is at least 4.0.

In some examples, the ratio of the average bending stiffness of the butt end portion to the average bending stiffness of the tip end portion is at least 5.0.

In some examples, a diameter of the shaft at the tip end is less than 0.300 inches.

In some examples, a golf club includes the shaft; a golf club head coupled to the tip end of the shaft; and a grip coupled to the butt end portion of the shaft.

In some examples, a mass ratio of the mass of the shaft to the mass of the grip is within a range of 1.1 to 1.3.

According to another aspect, the technology relates to a shaft for a golf club, including a tip end configured to couple to a golf club head; a butt end opposite to the tip end; and a butt end portion that extends in the tip-to-butt direction from 800 mm from the tip end to 950 mm from the tip end and has an average rate of change of bending stiffness in the tip-to-butt direction, wherein a rate ratio is at least 2.7 and is defined as a ratio of the rate of change of bending stiffness of the shaft in the tip-to-butt direction at any point within a portion of the shaft extending at least 10 mm along the tip-to-butt direction and being centered at a point having a maximum rate of change of bending stiffness; to the average rate of change of bending stiffness of the butt end portion.

In some examples, the rate ratio is at least 3.5.

In some examples, the rate ratio is at least 7.5.

In some examples, the portion of the shaft extends at least 50 mm along the tip-to-butt direction.

In some examples, the portion of the shaft extends at least 100 mm along the tip-to-butt direction.

In some examples, the shaft has a tip end portion extending in the tip-to-butt direction from 150 mm from the tip end to 300 mm from the tip end, and a ratio of the average bending stiffness of the butt end portion to an average bending stiffness of the tip end portion is at least 5.0. In some examples, a diameter of the shaft at the tip end is less than 0.290 inches.

In some examples, a golf club includes the shaft; a golf club head coupled to the tip end of the shaft; and a grip coupled to the butt end portion of the shaft.

In some examples, a mass of the shaft is less than 50 g, a mass of the grip is less than 40 g, and a mass ratio of the mass of the shaft to the mass of the grip is within a range of 1.1 to 1.3.

According to another aspect, the technology relates to a shaft for a golf club, including a tip end configured to couple to a golf club head; a butt end opposite to the tip end; a tip end portion that extends in a tip-to-butt direction from the tip end by at least 50 mm; a butt end portion that extends in a butt-to-tip direction from the butt end by at least 50 mm and has an average rate of change of bending stiffness in a tip-to-butt direction; and a middle portion between the tip end portion and the butt end portion, wherein a rate of change of bending stiffness in the tip-to-butt direction at a point in the middle portion is at least 2.7 times the average rate of change of bending stiffness of the butt end portion, and wherein a diameter of the shaft at the tip end is less than 0.300 inches.

In some examples, the rate of change of bending stiffness in the tip-to-butt direction at the point in the middle portion is at least 5.0 times the average rate of change of bending stiffness of the butt end portion, and the diameter of the shaft at the tip end is less than 0.285 inches.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Additional aspects, features, and/or advantages of examples will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure.

Due to the swing speeds and the shape of golf club heads, many golf clubs, or parts thereof, operate in a Reynolds number regime in which the state of the viscous boundary layer is typically laminar unless forced to a turbulent state by a tripping structure. On bluff bodies, such as the hosel of a golf club, the laminar boundary layer will separate creating a large wake with a relatively low-pressure region. This low pressure acting on the aft facing surface area results in a drag force that retards the speed of the clubhead at impact. In particular, hosels on golf clubs are often constructed having a circular (or nearly so) cross section. Circular cylinders at subcritical (prior to natural transition) Reynolds numbers have a relatively high drag coefficient as compared to those operating with a turbulent boundary layer. By forcing the transition to occur with a tripping structure the drag can be reduced with a resultant increase in clubhead speed. Due to the rotation of the golf club head, the location and dimensions of the tripping structures become important to create the transition from the laminar flow to the turbulent flow.

In addition to tripping structures on the hosel of the golf club head, the shape of the golf club head may also be altered to improve its aerodynamic properties. For instance, changing the shape of the golf club head, such as the striking face, crown, and sole, causes changes in drag experienced by the golf club head during a swing of the golf club head. As an example, what is commonly perceived as an improved aerodynamic shape to the golf club head is to have the crown and the sole meet a singular point at the aft of the golf club head, such as to form a teardrop shape of the golf club head that has a sharper trailing edge. The present technology, however, goes against that traditional perception of the teardrop shape while still lowering drag and improving the overall aerodynamic properties of the golf club head. For instance, the traditional teardrop shape causes a high closure angle of the crown and/or the sole. This high closure angle causes an earlier, or more forward, separation of the turbulent flow over the crown and the sole, which increases the pressure drag experienced by the golf club head during a swing. The present technology changes, and reduces, the closure angles of the crown and/or the sole to move the separation of the turbulent flow further towards the aft the golf club. These reduced closure angles result in a golf club head that may look less aerodynamic but actually results in a golf club that experiences less pressure drag forces and has overall improved aerodynamic properties. The changes to the closure angles of the crown and/or the sole may be accomplished, for example, by raising an aft portion of the skirt further above the ground plane and/or increasing the thickness of the aft portion of the skirt.

depicts a front view of an example golf club headincluding a plurality of tripping structures.depicts an enlarged front view of a hosel of the golf club head of.are discussed concurrently. The golf club headis metal-wood type golf club head, such as a driver or a fairway metal. The golf club headincludes a striking face, a crown, a toe region, a heel region, and a sole. The crownand the solemay be attached to the striking face. For instance, the crownis attached to a topside of the striking faceand the soleis attached a bottom side of the striking face.

The golf club headalso includes a hosel. The hoselis used to attach a shaft (not depicted) to the golf club head. The hoselmay be formed into at least a portion of the crownand the heel portion. The hoselmay also include a ferrule or components of an interchangeable shaft system.

The hoselalso includes a plurality of tripping structures. In the example depicted, the tripping structuresare formed as elongate ridges extending from the top of the hosel towards the sole. This particular pattern has three substantially parallel ridges on both the heelward and toeward side of the hosel. The height of the ridges (e.g., the distance the ridges protrude from the surface of the hosel) may be between 0.005 inches and 0.03 inches. In some examples, the height of the ridges is between 0.009 inches and 0.015 inches.

The length (L) of the tripping structuresmay be between 30-70 mm. In some examples, the length (L) of the tripping structuresmay be greater than 40 mm. The length of the tripping structuresmay also be considered as two components, a first length component that extends through a ferrule and any additional hosel components (e.g., adjustable shaft components, rings, sleeves, etc.) and a second length component extending across the body of the club head, such as the heel regionof the club head. The second length component is represented as Lin, and represents the length of the tripping structuresacross the body of the club head. The second length component (L) may be between 15-35 mm, 20-30 mm, and/or may be at least 20 mm. In some examples, the heelward tripping structures and the toeward tripping structuresmay have the same length. In other examples, the heelward tripping structuresmay have a greater length than the toeward tripping structures. In yet other examples, the toeward tripping structuresmay have a greater length than the heelward tripping structures.

depict top views of the hosel of the golf club head of.depicts a toe-side view of the golf club head of, anddepicts a heel-side view of the golf club head of. As can be seen from, the golf club headincludes a rearmost point(e.g., a trailing edge) and a frontmost point(e.g., a leading edge).are discussed concurrently.

depicts a view down the shaft axis (e.g., an axis formed by a shaft that would be connected to the hosel) of the golf club headand indicates the angular positions of the tripping structures with respect to the shaft axis. In, the three toeward tripping structuresare individually labeled as a first toeward tripping structureA, a second toeward tripping structureB, and a third toeward tripping structureC. The three heelward tripping structures are also individually labeled as a first heelward tripping structureD, a second heelward tripping structureE, and a third heelward tripping structureF.

The locations or positions of the tripping structuresaccount for the rotational movement of the club head during a swing of a golf club head. For instance, during the downswing of golf club, the heelward tripping structuresD-F are more exposed to the airflow, whereas at impact and during the follow through, the toeward tripping structuresA-C are more exposed to the airflow. Due to the toeward tripping structuresA-C being located more towards the striking face, the toeward tripping structuresA-C also provide tripping effects during the downswing of the golf club head.

The location or position of each of the tripping structuresmay be described as an angular position around the shaft axis. The angular positions may be described as relative to a toe-to-heel axisor a front-to-back axis. The front-to-back axisis an axis that runs from the front of the golf club headto the back of the golf club head, and the toe-to-heel axisis an axis that runs from the toe to heel of the golf club headand is substantially perpendicular to the front-to-back axis. For instance, the front-to-back axismay be perpendicular to a plane defined by the striking face. In the examples used herein, the front-to-back axishas a zero-degree position pointing forward of the golf club head. For instance, the zero-degree shaft-axis angular position may correspond to a direction forward of the golf club headand perpendicular to the plane defined by the striking face. The origin of the front-to-back axisand the toe-to-heel axismay be located at the center of the hosel (e.g., at the shaft axis).

The tripping structureson the toeward side of the front-to-back axisare referred to as the toeward tripping structures, and the tripping structuresthat are on the heelward side of the front-to-back axisare referred to as the heelward tripping structures. As measured from the front-to-back axis, the first toeward tripping structureA is located 30 degrees around the shaft axis, as represented by angle α, as measured in a clockwise direction. The second toeward tripping structureB is offset by 15 degrees around the shaft axis from the first toeward tripping structureA. The third toeward tripping structureC is offset by 15 degrees from the third toeward tripping structureC. In other words, the second toeward tripping structureB is located 45 degrees around the shaft axis, as represented by angle α, and the third toeward tripping structureC is located 60 degrees around the shaft axis, as represented by angle α.

Of note, the toeward tripping structuresA-C are located towards the front of the golf club headfrom the toe-to-heel axis. In other words, the toeward tripping structures are located between 0-90 degrees around the shaft axis as measured from the front-to-back axis. By positioning the toeward tripping structuresA-C towards the front of the golf club head, the toeward tripping structuresA-C are able to provide the tripping effect for more of the downswing of the golf club as the golf club rotates from an open position to a closed position.

As also measured from the front-to-back axis, the first heelward tripping structureD is located −60 degrees around the shaft axis, as represented by the angle β. The second heelward tripping structureE is offset by 15 degrees around the shaft axis from the first heelward tripping structureD. The third heelward tripping structureF is offset by 15 degrees around the shaft axis from the second heelward tripping structureE. In other words, the second heelward tripping structureE is located −75 degrees around the shaft axis, as represented by angle β, and the third heelward tripping structureF is located −90 degrees around the shaft axis, as represented by angle. In some examples, the heelward tripping structures may be more easily measured from the toe-to-heel axis. For instance, the third heelward tripping structureF is aligned with, or parallel to, the heel-to-toe axis.

The first toeward tripping structureA may be referred to as the frontmost toeward tripping structureA, and the first heelward tripping structureA may be referred to as the frontmost heelward tripping structureD. The frontmost toeward tripping structureA and the frontmost heelward tripping structureD in the example depicted are positioned 90 degrees apart from one another.

The angular positions of the tripping structuresdescribed above are for a particular example, and some variations on the angular positions may also be implemented to achieve the tripping effects described herein. For example, the toeward tripping structuresmay be located within 0-80 degrees, 10-80 degrees, 10-70 degrees, and/or 30-70 degrees around the shaft axis as measured from the front-to-back axis. The heelward tripping structuresmay be located between −30 to −90, −50 to −90, −60 to −90, and/or −40 to −110 degrees around the shaft axis as measured from the front-to-back axis.

The toeward tripping structuresand/or the heelward tripping structuresmay be spaced from one another by an angular amount of 5-25 degrees and/or 10-20 degrees. In some examples, such as the one depicted in, the toeward tripping structuresA-C and/or the heelward tripping structuresD-F may be evenly spaced from one another.

One or more of the toeward tripping structuresA-C may be symmetrically positioned about radial line of 350 degree (i.e., −10 degree) shaft-axis angle from one or more of the heelward tripping structuresD-F. For instance, a position of the toeward tripping structure and a position of the heelward tripping structure may be substantially symmetric about a line extending along a 350 degree shaft-axis angle. Such symmetry may improve the overall aerodynamic properties of the hosel. As an example, a toeward tripping structure being positioned at a shaft-axis angular position of 0-80 degrees measured around the shaft axis, and a heelward tripping structure may be positioned, symmetrically about the 350 degree line, at a shaft-axis angular position of 260-340 degrees measured around the shaft axis. the toeward tripping structure is located at a shaft-axis angular position of 30-60 degrees and the heelward tripping structure is located at a shaft-axis angular position of 280-310 degrees.

The heights, lengths, and locations of the tripping structuresdiscussed herein are able to trigger a transition from a laminar flow to a turbulent flow around the hosel at the Reynolds numbers and swing speeds typically associated with the swinging of a golf club head. For instance, the tripping structuresmay be configured to cause tripping from laminar flow to turbulent flow around the hosel at a Reynolds number characteristic of flow conditions experienced by golfers (such as less than 30,000), as the hoselof the golf club headusually is within a 20,000 to 50,000 Reynolds number regime. In addition, the dimensions and locations of the tripping structuresare important for causing the transition from the laminar flow to turbulent flow in the proper location. For example, if the tripping occurs too early, the flows will fully separate and not reattach, or if there is a very strong favorable gradient, the flows will relaminarize and then separate-both of which may actually increase drag. The present dimensions and locations of the tripping structuresprevent such adverse phenomenon even when the golf club head rotates during a golf swing.

While the tripping structuresshown inare ridges that protrude outwardly from the hosel, in other examples, the tripping structuresmay take different forms. For instance, the tripping structuresmay be formed as grooves rather than ridges. The depth of the grooves may be the same as the height of the ridges discussed herein. The grooves may also have similar lengths and positions as the ridges. In some examples, grooves and ridges may be utilized, and the height may be considered an amplitude measured from the peak of the ridge to the valley of the groove.

The tripping structuresmay also be formed from tooling marks, that have adequate roughness to transition the boundary layer, positioned in similar locations and orientations as the ridges discussed above. Additional patterns, such as three-dimensional sine waves that are roughly axisymmetric with respect to the shaft or hosel axis, may also be used. The sine waves may also be a function of both position along the shaft or hosel axis and the circumferential position around the hosel. A three-dimensional pattern of interconnect ridges, such as a hexagonal pattern, may also be used as tripping structures. Dimples or pimples (e.g., the opposite of dimples) may also be used as tripping structuresin some examples.

depicts a partial perspective view of a golf club headwith an adjustable hoselincluding tripping structures. As with the other examples described above, the golf club headhas a striking faceand a hoselextends from the crown. The adjustable or configurable hoselmay be a part of a shaft connection system, and/or the configurable hoselmay be adjusted to change characteristics of the golf club head, such as the loft and/or lie characteristics of the golf club head.

The example configurable hoseldepicted inis similar to the SUREFIT® hosel system from the Acushnet Company of Fairhaven, Massachusetts. The configurable hoselincludes a fixed portionattached to the club headnear the crownand two configurable or adjustable components: a rotatable ringand a rotatable sleeve. The fixed portion, the rotatable ring, and the rotatable sleeveeach include a series of tangs and notches. When the configurable hoselis tightened together, the tangs fit into the notches. By rotating the ringand the sleeve, multiple different configuration states for the configurable hoselmay be achieved. In the example depicted, the ringincludes four different settings as indicated by letter markings A-D, with each setting including a different tang on the ring. The sleevesimilarly has four different settings as indicated by number markings 1-4, with each setting including a different tang on the sleeve. The configuration state of the configurable hoselcorresponds to the settings of the ringand the sleevethat are aligned with an alignment reference indicator on the fixed portion. A ferrulemay also be included. Additional details regarding a similar configurable hosel system may be found in U.S. Pat. No. 9,403,067, titled “Interchangeable Shaft System,” which is incorporated herein by reference in its entirety.

The configurable hoselalso includes tripping structures. The tripping structuresmay be divided into separate pieces or portions corresponding to the number of different components in the configurable hosel. In the example depicted, there are four components of the adjustable hosel—the fixed portion, the rotatable ring, the rotatable sleeve, and the ferrule. The tripping structuresextend across each of the four components. To allow for adjustment of the adjustable hosel, each of the tripping structures are separated into four pieces corresponding to the four different components of the adjustable hosel. For instance, each tripping structuremay have a first piece on the ferrule, a second piece on the sleeve, a third piece on the ring, and a fourth piece on the fixed portion. Each of the pieces of the tripping structuremay be separated from one another, such as by a cut, or the pieces of the tripping structuresmay be separately formed as part of the respective components, such as the ringand the sleeve. Accordingly, as the adjustable components of the hosel(e.g., the ringand the sleeve) are rotated, the corresponding piece of the tripping structuremove with the respective adjustable component. For example, the pieces of tripping structureslocated on the ringmove with the ringas the ringis rotated.

The number and/or positions of the tripping structuresmay be based on the number of different settings available from the adjustable components of the hosel. In the example depicted, the ringand the sleeveeach have four possible settings (e.g., settings A-D and settings 1-4). Accordingly, four tripping structuresmay be incorporated into the hosel. Each of the four setting positions on the ringand the sleeveare offset by 90 degrees (e.g., 360 degrees divided by four). Thus, the four tripping structuresare also offset from one another by 90 degrees. As a result, in any setting combination of the ringand the sleeve, the respective pieces of the tripping structuresalign with other pieces of the tripping structuresto form the full-length tripping structures. With the offsets of 90 degrees, the tripping structuresmay be located in the angular positions discussed above with respect to. The pieces of the tripping structureson the adjustable components of the hoselmay also be made such that all the pieces have the same size and shape (e.g., same thickness, length, width, cross-section, etc.), which further allows for consistent forming of the full tripping structuresin any of the settings of the adjustable components.

As another example, if the adjustable components have only three settings, three tripping structuresmay be included and may be offset by 120 degrees, whereas if the adjustable components have five settings, five tripping structuresmay be incorporated and may be offset by 72 degrees. The number of tripping structuresmay be equal to the number of settings, and the offset angle of the tripping structuresmay be based on the offset angles of the different settings of the adjustable components. In some examples, multiple tripping structuresmay be included on each of the different settings (such as the tangs of the ring). In such examples, the number of tripping structuresmay be equal to a multiple of the number of settings. For instance, for an adjustable component with four settings, 4, 8, 12, or 16 tripping structuresmay be included on the hosel.

depicts a partial top view golf club headwith a hoselwith tripping structures. As with the other examples described above, the hoselextends from the crown. In this example, however, only two tripping structuresare included on the hosel. The two tripping structuresare offset from one another by about 90 degrees. Both of the tripping structuresare incorporated on the front half of the hoselas well. For instance, both tripping structuresare located on the striking-face side of the hoselrather than rear side of the hosel. As discussed above, by incorporating the tripping structureson the front side of the hosel, the tripping structurescause the tripping effects at more points during a golf swing due to the rotation of the golf club head.