GOLF CLUB

Abstract

A golf club includes a club head having a sole with an improved region. In a first soled position at which the golf club is oriented at a first lie angle, the golf club exhibits a first face angle. In a second soled position at which the golf club is oriented at a second lie angle less than the first lie angle by no less than 1 degree, the golf club exhibits a second face angle that is within 1 degree of the first face angle. And in a third soled position at which the golf club is oriented at a third lie angle greater than the first lie angle by no less than 1 degree, the golf club exhibits a third face angle that is within 1 degree of the first face angle.

Description

BACKGROUND

This disclosure relates generally to the field of golf clubs. More particularly, it relates to a golf club having a club head with an improved sole region.

SUMMARY

Golf clubs are generally designed to be oriented at a designated lie angle. But because a golfer's hands may be set up higher or lower than expected, the club rarely exhibits that designated lie angle when soled at address. Indeed, soled lie angle at address for the same club can vary by more than 20 degrees from golfer to golfer.

Such changes in soled lie angle typically create changes in the club head's face angle at address. For example, the club face will tend to open as soled lie angle increases and will tend to close as soled lie angle decreases. This change in face angle is undesirable because a golfer may set a club on the ground in a store or on a tee box and visualize the face angle of the club and the direction the face is pointing to align their shot. A club face that is unexpectedly open or closed because of a golfer's soled lie angle differing from the designated lie angle of the club can frustrate this endeavor, leading to misdirected shots. There is thus a need and a desire to have a more constant, preferably square, face angle at address regardless of the soled lie angle of the golfer.

A golf club according to one or more aspects of the present disclosure may thus include a shaft, which has a butt end and a tip end, and a club head. The club head may include: a volume greater than 360 cubic centimeters; a striking face at a front portion; a rear portion opposite the striking face; a heel portion; a hosel portion shaped to receive therein the tip end of the shaft; a toe portion opposite the heel portion; a crown; and a sole opposite the crown. The sole may be configured such that: (i) in a first soled position at which the golf club is oriented at a first lie angle between 40 and 60 degrees, the shaft is in a first rotational position and the golf club exhibits a first face angle; (ii) in a second soled position at which the golf club is oriented at a second lie angle between 40 and 60 degrees and less than the first lie angle by no less than 1 degree, the shaft is in a second rotational position, which is rotationally offset from the first rotational position in a first direction, and the golf club exhibits a second face angle that is within 1 degree of the first face angle; and (iii) in a third soled position at which the golf club is oriented at a third lie angle between 40 and 60 degrees and greater than the first lie angle by no less than 1 degree, the shaft is in a third rotational position, which is rotationally offset from the first rotational position in a second direction opposite the first direction, and the golf club exhibits a third face angle that is within 1 degree of the first face angle.

And another golf club according to one or more aspects of the present disclosure may include: a shaft having a butt end and a tip end; a grip attached to the butt end of the shaft; and a club head. The club head may in turn include: a volume greater than 400 cubic centimeters; a striking face at a front portion; a rear portion opposite the striking face; a heel portion; a toe portion opposite the heel portion; a hosel portion shaped to receive therein the tip portion of the shaft; a crown; and a sole opposite the crown. And the sole may be configured such that: (i) in a first soled position at which the golf club is oriented at a first lie angle between 40 and 60 degrees, the shaft is in a first rotational position and the golf club exhibits a first face angle; (ii) in a second soled position at which the golf club is oriented at a second lie angle between 40 and 60 degrees and less than the first lie angle by no less than 5 degrees, the shaft is in a second rotational position, which is rotationally offset from the first rotational position in a first direction, and the golf club exhibits a second face angle that is within 0.5 degrees of the first face angle; and (iii) in a third soled position at which the golf club is oriented at a third lie angle between 40 and 60 degrees and greater than the first lie angle by no less than 5 degrees, the shaft is in a third rotational position, which is rotationally offset from the first rotational position in a second direction opposite the first direction, and the golf club exhibits a third face angle that is within 0.5 degrees of the first face angle.

These and other features and advantages of the golf clubs and manufacturing methods thereof according to the various aspects of the present disclosure will become more apparent upon consideration of the following description, drawings, and appended claims. The description and drawings described below are for illustrative purposes only and are not intended to limit the scope of the present invention in any manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 show, respectively, front elevation and top plan views of an exemplary golf club head;

FIG. 3 shows a front elevation view of a golf club including the golf club head of FIGS. 1 and 2;

FIGS. 4A-4C show front elevation views of the golf club of FIG. 3 at different soled lie angles;

FIGS. 5A-5C show top down views of the golf club of FIG. 3 at the different soled lie angles shown in FIGS. 4A-4C;

FIGS. 6A and 6B show perspective views of a golf club head in accordance with one or more aspects of the present disclosure;

FIG. 7 shows a comparison of a golf club with the golf club head of FIGS. 6A and 6B with various prior clubs;

FIGS. 8A-8C show various rotational positions of the shaft of a golf club with the golf club head of FIGS. 6A and 6B;

FIG. 9 is a graph showing the relationship of shaft rotational position and soled lie angle at various constant face angles;

FIG. 10 shows a method of determining sole geometry for manufacturing a golf club in accordance with one or more aspects of the present disclosure; and

FIG. 11 shows a computer system capable of executing the method shown in FIG. 10.

DETAILED DESCRIPTION

Shown in FIGS. 1 and 2 is an exemplary golf club head 100. The club head 100 may be a hollow-type club head such as that for a driver, fairway wood, or hybrid golf club. A volume of the club head may be greater than or equal to 100 cubic centimeters, or preferably greater than or equal to 175 cubic centimeters. In the particular case of a driver-type golf club, the volume may preferably be greater than or equal to 360 cubic centimeters, and in certain aspects it may be greater than or equal to 400 cubic centimeters. The club head 100 may generally be formed from metallic and/or nonmetallic materials such as any one or a combination of aluminum, stainless steel, titanium, composites, polymeric materials, and any other suitable material.

The club head 100 may include a front portion 110, which may have a striking wall including a striking face 112 for contacting a golf ball, and a rear portion 120 opposite the striking face 112. The striking face 112 may include a face center 114, which is a point on the striking face 112 that is equidistant from the striking face periphery in both the horizontal direction and in the vertical direction, as set out in the United States Golf Association's Procedure for Measuring the Flexibility of a Golf Club Head (Revision 2.0, Mar. 25, 2005), in which “face center” is described as being identifiable using a designated template for such purpose. The club head 100 may further include a toe portion 130, a heel portion 140 opposite the toe portion 130, a sole portion or sole 150, and a top portion or crown 160 opposite the sole portion 150. The heel portion 140 may include a hosel portion 142 shaped and configured to receive and secure a portion of a shaft of the golf club. The club head 100 may include a club head center of gravity at the location 116. And the club head may have a designated loft angle, which, as used herein, refers to the angle formed between a virtual vertical hosel plane containing an axis 144 of the hosel portion 142 and a virtual striking face plane substantially parallel to the striking face 112 at the face center 114. The designated loft angle of the club head 100 may be equal to or less than 25 degrees, more preferably equal to or less than 13 degrees, but in certain other aspects it may be greater than 25 degrees.

FIG. 3 shows the golf club head 100 with a tip end 172 of a shaft 170 received by and secured within the hosel portion 142. The shaft 170 may include a grip 176 attached to a butt end 174 of the shaft 170. FIG. 3 thus shows a complete golf club 200, which may include a club center of gravity at location 210. The golf club 200 is shown in FIG. 3 in the reference position, which, as used herein, refers to an orientation of the club head 100 relative to a virtual ground plane 220 in which the club head is permitted to rest on the ground plane 220 such that the sole portion 150 of the club head contacts the ground plane 220 at one or more sole contact points 152 between leading and trailing edges of the sole portion. Further, in the reference position the hosel axis 144 of the hosel 142 (and thus an axis 178 of the shaft 170) is oriented such that the club head 100 is at its designated loft angle relative to the virtual ground plane 220 and the hosel and shaft axes lie at the club head's designated lie angle 230, which, as used herein, refers to the intended angle formed between the ground plane 220 and the shaft axis 178. Also, in the reference position, a virtual vertical plane coplanar with the hosel axis 144 forms an intersection with the virtual striking face plane, the intersection being a virtual line extending horizontally in the heel to toe direction.

In some examples, the golf club 200 may include a “designated lie angle,” which is an intended lie angle at which the golf club may be positioned when in a soled position. But while the golf club 200 may have a designated lie angle at the reference position, in practice the golf club 200 is rarely in that reference position at address. Indeed, soled lie angles at address for a vast majority of golfers range between 40-50 degrees. The range of soled lie angles from approximately 40 degrees to approximately 60 degrees may be selected to accommodate a broad population of golfers. Most golfers (approximately 90 percent) exhibit soled lie angles between approximately 40 degrees and approximately 50 degrees at address. The extended range to 60 degrees may accommodate additional golfers who exhibit more upright stances, including taller golfers, golfers with longer arms, golfers who grip the club higher on the grip, and golfers with particular swing styles that result in higher hand positions at address. By configuring the improved sole geometry to maintain substantially constant face angle across this 40 to 60 degree range, the golf club may provide consistent face angle presentation for substantially all golfers regardless of their physical characteristics or setup preferences. FIGS. 4A-4C thus show the golf club 200 at different soled lie angles. In these Figures (as well as in FIG. 3) the golf club is shown in the “soled position,” which as used herein refers to an orientation of the club head 100 relative to the virtual ground plane 220 in which the sole portion of the club head contacts and is permitted to rest freely on the virtual ground plane 220, but with the shaft 170 held at a constant, predetermined lie angle. Thus, “soled position” of the golf club 200 may differ from its reference position and takes into account a golf club's structure, mass distribution, and sole contour. Unless otherwise noted, all dimensions and positional characteristics described herein with regard to a golf club head are intended to be measured or determined with the golf club head oriented in the soled position. As such, “soled lie angle” refers to the specific angle at which a golfer holds a golf club during the setup position prior to initiating a swing. The soled lie angle may be distinct from the designated lie angle and the soled lie angle may vary based on a golfer's stance, posture, and personal preferences and the soled lie angle may influence the trajectory and accuracy of a golf shot. To illustrate, FIG. 4A shows a lower soled lie angle 232 resulting from a golfer's hands having lowered relative to the designated lie angle at address; FIG. 4B shows a higher soled lie angle 234 resulting from a golfer's hands having risen relative to the designated lie angle at address; and FIG. 4C shows a soled lie angle 236, which may be the designated lie angle, therebetween. As also shown, changes in soled lie angle may result in changes in the contact point 152 between the sole portion and the ground plane 220. For example, the contact point 152 may move toe-ward as soled lie angle increases and may move heel-ward as soled lie angle decreases.

FIGS. 5A-5C show top down views of the golf club head 100 at the soled lie angles shown in FIGS. 4A-4C, respectively. As shown, these differences in soled lie angle at address may result in corresponding changes in the face angle of the club head 100. Face angle, as used herein, refers to 90 minus the angle formed between (i) a hosel axis and (ii) a virtual line perpendicular to the striking face plane and passing through the face center, where both the hosel axis and the virtual line are projected in the virtual ground plane. As such, face angle may represent a measurement of how square the club face is to an intended target line (e.g., where 0 degrees would represent the club face being aligned with the target line). As shown in each of FIGS. 5A-5C, the shaft and hosel axes (and thus the virtual vertical plane in which they extend) extend into the page toward the ground plane and in the top and bottom directions of the page. FIG. 5C shows the club head 100 at a neutral, or square, face angle 246. FIG. 5A in turn shows the club head 100 at a closed face angle 242. And FIG. 5B shows the club head 100 at an open face angle 244. Soled face angle at address is a function of the center of gravity 210 of the entire golf club—including the club head, shaft, and grip—along with contour and exterior geometry of the sole portion. These combine to create a statics problem to find where the golf club orients itself to reach equilibrium. As shown previously, depending on the soled lie angle at address, the contact point on the sole with the ground plane may be different, which means normal forces from the ground plane will be pointed in different directions. This results in the golf club having different equilibriums for different soled lie angles, thereby causing the differing face angles shown in FIGS. 5A-5C.

FIGS. 6A and 6B thus show the sole portion 350 of a golf club head 300 in accordance with one or more aspects of the present disclosure. Except where specified, this golf club head may be identical to the golf club head 100. But unlike the club head 100, the sole portion 350 of the club head 300 may represent the results of algorithms that take into account (i) the contour of the sole portion, (ii) the center of gravity of the entire club, (iii) soled lie angle at address, and (iv) face angle to define an improved region 354 that is fit to a remainder of the sole portion and that ensures that face angle is substantially constant at a variety of soled lie angles at address.

As shown in FIGS. 6A and 6B, the improved region 354 may be an ellipsoid, which is a versatile shape as it provides both front-to-rear curvature and heel-to-toe curvature, but the improved region may take other shapes. The improved region 354 may also have curvature that differs from the remainder of the sole portion 350 in heel-to-toe and/or front-to-rear directions of the club head. The improved region 354 may have a curvature that is constant in the front-to-rear direction and/or in the heel-to-toe direction, or that curvature may be, and preferably is, non-constant in the front-to-rear direction and/or in the heel-to-toe direction. For example, the heel-to-toe curvature of the improved region 354 may have a first average radius of curvature that differs from a second average radius of curvature of the front-to-rear curvature, average radius of curvature being defined as the radius of curvature taken at points of the improved region 354 spaced apart from each other by a constant increment over a predetermined distance of the sole. In some aspects the first average radius of curvature may be greater than the second average radius of curvature. In some aspects, the first average radius of curvature may be between approximately 3 centimeters and approximately 12 centimeters, or preferably between 4 centimeters and 8 centimeters. In some aspects, the second average radius of curvature may be between approximately 1 centimeter and approximately 6 centimeters, or preferably between approximately 2 centimeters and approximately 5 centimeters. As shown in FIGS. 6A and 6B, the improved region 354 may form less than an entirety of the sole portion 350, and it may be positioned proximate the striking face 312. But in other aspects the improved region may constitute most or all of the sole portion 350.

The improved region 354 may include curvature in both the heel-to-toe direction and the front-to-rear direction. The front-to-rear curvature of the improved region 354 may contribute to allowing the club face to open and close appropriately as soled lie angle changes. In some prior approaches, sole contours configured to reduce face angle variation have included curvature primarily or exclusively in the heel-to-toe direction, with little or no curvature in the front-to-rear direction. By contrast, the improved region 354 may include meaningful curvature in both directions, which may enable the improved region 354 to more precisely control the equilibrium position of the club head across the range of soled lie angles. The combination of heel-to-toe curvature and front-to-rear curvature in the improved region 354 may thus provide enhanced face angle consistency compared to sole contours having curvature in only one direction. In some aspects, the improved region 354 may have a non-constant radius of curvature in the heel-to-toe direction and/or in the front-to-rear direction. A non-constant radius of curvature may provide advantages over a constant radius of curvature, such as that of a cylindrical surface. For example, the relationship between changes in soled lie angle and the corresponding changes in contact point location, normal force direction, and equilibrium position may be non-linear. A sole contour having a constant radius of curvature may not fully account for this non-linear relationship, potentially resulting in face angle variation that increases at the extremes of the soled lie angle range. By contrast, a sole contour having a non-constant radius of curvature, such as that of an ellipsoid, may be configured to account for the non-linear relationship between soled lie angle and face angle, potentially providing more consistent face angle across the entire range of soled lie angles. In some aspects, the radius of curvature of the improved region 354 in the heel-to-toe direction may vary along the heel-to-toe extent of the improved region 354, and/or the radius of curvature in the front-to-rear direction may vary along the front-to-rear extent of the improved region 354.

The improved region 354 may function by generally reducing the spatial extent of the club head proximate the heel side of the sole portion and increasing the spatial extent of the club head proximate the toe side of the sole portion, thereby helping ensure that the club head opens more in low soled lie angles at address and closes more in high soled lie angles at address. As shown in FIGS. 6A and 6B, the improved region 354 may be formed as an integral part of the sole portion 350 that may blend with the rest of the sole portion. Compared with other supposed solutions that may rely on, say, interchangeable sole pieces, shims, washers, and screws that add significant weight to the club head and could negatively impact center of gravity and moment of inertia, the integral improved region 354 may help reduce weight, thereby allowing discretionary mass to be placed elsewhere within the club head. The improved region 354 may also help reduce manufacturing costs relative to those other solutions, as only one tool may be needed and separate pieces may not be required. And the improved region 354 may improve ease of use over other supposed solutions, as it does not rely on the user to select, say, a correct number of shims or a correct sole piece among a plurality of different sole pieces, which could lead to significant user error.

The improved region 354 may function by modifying the spatial extent of the sole portion 350 in a manner that counteracts the natural tendency of the club face to close at low soled lie angles and to open at high soled lie angles. More specifically, the improved region 354 may generally reduce the spatial extent of the club head proximate the heel side of the sole portion 350, which may cause the club head to open more than it otherwise would at low soled lie angles. Conversely, the improved region 354 may generally increase the spatial extent of the club head proximate the toe side of the sole portion 350, which may cause the club head to close more than it otherwise would at high soled lie angles. These modifications to the sole geometry may be configured such that the tendency of the club face to open at low soled lie angles (due to the modified sole geometry) substantially cancels the natural tendency of the club face to close at low soled lie angles, and the tendency of the club face to close at high soled lie angles (due to the modified sole geometry) substantially cancels the natural tendency of the club face to open at high soled lie angles. The result may be a club head that exhibits a substantially constant face angle across the range of soled lie angles. Some prior approaches to addressing face angle variation across soled lie angles have employed adjustable sole mechanisms or interchangeable sole pieces. For example, some prior golf clubs have included sole plates that can be adjusted in height or replaced with sole plates of different heights to modify face angle at a particular lie angle. While such approaches may provide some ability to customize face angle, they may have several disadvantages compared to the improved region 354 described herein. First, adjustable and interchangeable sole systems may add significant weight to the club head, which may negatively impact the location of the center of gravity and/or the moment of inertia of the club head. By contrast, the improved region 354 may be formed as an integral part of the sole portion 350, potentially reducing weight and allowing discretionary mass to be placed elsewhere within the club head to optimize center of gravity location and moment of inertia. Second, adjustable and interchangeable sole systems may increase manufacturing costs due to the need for multiple components, additional tooling, and more complex assembly processes. The improved region 354 may be manufactured using a single tool and may not require separate pieces, potentially reducing manufacturing costs. Third, adjustable and interchangeable sole systems may rely on the user to correctly select and install the appropriate sole piece or adjustment setting, which may lead to user error. The improved region 354 may provide substantially constant face angle across a range of soled lie angles without requiring any user adjustment or selection, potentially improving ease of use and reducing the likelihood of user error.

Included within the improved region 354 may be a channel 355 that may be defined by edges 356 and 357 extending substantially in a heel-to-toe direction and that has a surface 358 recessed from a remainder of the sole portion 350. The golf club may be configured such that, when the golf club is in soled positions, over a range of soled lie angles from approximately 40 degrees to 60 degrees, the center of gravity of the club head, across most lie angles within the range of approximately 40 degrees to 60 degrees, is substantially vertically aligned with a centerline 359 of the channel 355. Relatedly, preferably across all soled lie angles within the range of approximately 40 degrees to 60 degrees, the center of gravity of the club head is vertically aligned with a location on the sole between the edges 356 and 357. The edges of the channel may therefore provide for multiple contact points of the club head 300 with the ground plane at address, thereby adding stability to the club head, ensuring that the club head contacts the ground plane only in the improved region 354, and preventing the club head from wobbling about a single contact point as a result of movement of a golfer's hands.

The channel 355 formed in the improved region 354 may provide stability to the club head at address by creating multiple contact points with the ground plane. Without the channel 355, the club head resting on the curved improved region 354 may tend to settle at a single contact point corresponding to the lowest point of the curved surface. In such a configuration, movement of the golfer's hands at address may cause the club head to wobble about the single contact point, potentially disrupting the golfer's alignment and concentration. The channel 355 may address this issue by providing two contact points—one at or near each edge 356, 357 of the channel 355—which may prevent such wobbling and provide a more stable platform for the club head at address. The centerline 359 of the channel 355 may correspond to a balance point of the club head, such that the center of gravity of the club head is substantially vertically aligned with the centerline 359 when the club head is in a soled position. By positioning the channel 355 such that its centerline 359 corresponds to this balance point, the club head may naturally settle into a stable position with contact points on either side of the balance point.

FIG. 7 shows a comparison of a golf club with the golf club head 300 versus various prior clubs. As shown for each of comparative examples 1-4, the face angle becomes progressively more open as soled lie angle increases. Indeed, face angle may open by 3-6 degrees from a low soled lie angle of 40 degrees to a high soled lie angle of 60 degrees. On the other hand, the golf club with the improved region 354 may maintain a nearly constant face angle, varying within a range of 1 degree, or even more preferably within a range of as little as 0.1 degree, from a low soled lie angle of 40 degrees to a high soled lie angle of 60 degrees. More specifically, FIG. 7 shows that the face angle of the club head 300 may be substantially square, i.e., at or about 90 degrees between the hosel axis and the virtual line perpendicular to the striking face plane as projected in the virtual ground plane, at a first soled position having a first soled lie angle of 50 degrees. The face angle of the club head 300 may also be substantially square at a second soled position having a second soled lie angle less than the first lie angle by no less than 5 degrees, e.g., 40 degrees. And the face angle of the club head 300 may also be substantially square at a third soled position having a third soled lie angle greater than the first soled lie angle by no less than 5 degree, e.g., 60 degrees. The face angle of the shafted club head 300 at the second soled position may thus be within 0.5 degree, and more preferably within 0.2 degree, of the face angle of the club head at the first soled position, and the face angle of the shafted club head 300 at the third soled position may also be within 0.5 degree, and more preferably within 0.2 degree, of the face angle of the club head at the first soled position.

In simulation, golf clubs having the improved sole geometry described herein have been shown to maintain face angle within approximately 0.1 degrees across a range of soled lie angles from 40 degrees to 60 degrees. By contrast, conventional driver-type golf clubs typically exhibit face angle variation of approximately 3 to 6 degrees across the same range of soled lie angles. The improved sole geometry may thus represent an improvement of approximately 30 to 60 times over conventional clubs with respect to face angle consistency. This dramatic reduction in face angle variation may be unexpected, as prior approaches to reducing face angle variation—such as adjustable sole plates, interchangeable sole pieces, and hosel adjustment mechanisms—have not achieved comparable results. The magnitude of this improvement may provide golfers with significantly enhanced ability to align shots consistently regardless of their individual stance, posture, or hand position at address. The various face angle tolerances disclosed herein—including within 1 degree, within 0.5 degrees, and within 0.2 degrees—may reflect different levels of manufacturing precision and quality control. In simulation, the improved sole geometry may achieve face angle variation of approximately 0.1 degrees or less across the range of soled lie angles. In manufactured golf clubs, face angle variation within approximately 1 degree may be achievable with standard manufacturing processes and tolerances. Tighter face angle variation, such as within 0.5 degrees or within 0.2 degrees, may be achievable with more precise manufacturing processes, tighter quality control, and/or selection of components (such as shafts and grips) having more precisely controlled mass properties. Even the 1 degree tolerance may represent a significant improvement over conventional clubs, which as noted above may exhibit face angle variation of 3 to 6 degrees across the same range of soled lie angles. Thus, a golf club achieving face angle variation within 1 degree may represent at least a 3-fold improvement over conventional clubs, while a golf club achieving face angle variation within 0.2 degrees may represent at least a 15-fold improvement.

To facilitate this nearly constant face angle, the shaft 370 of a soled golf club with the club head 300 may naturally rotate about a shaft axis 378 as the club is supported at the butt end of the shaft and soled lie angle increases or decreases. For example, FIGS. 8A-8C show respectively first 371, second 373, and third 375 rotational positions of the shaft 370 at the first, second, and third soled positions discussed above. The second rotational position 373 may be rotationally offset from the first rotational position 371 by more than 1 degree, and preferably by at least 2 degrees, in a first, clockwise rotational direction when viewed along the shaft axis 378. And the third rotational position 375 may be rotationally offset from the first rotational position by more than 1 degree, and preferably by at least 2 degrees, in a second, counterclockwise rotational direction when viewed along the shaft axis 378. Thus, the shaft 370 may naturally rotate about the shaft axis 378 more than 1 degree, and preferably by at least 2 degrees, for a 10 degrees change in soled lie angle. FIG. 9 shows, for constant face angles, shaft rotational positions as soled lie angle increases from 40 degrees to 60 degrees for a 10 degree driver having a designated lie angle of 60 degrees.

The improved sole geometry of the club head 300 may function by enabling the shaft to rotate about its longitudinal axis when the golf club is supported at the butt end of the shaft and the club head is permitted to rest on a ground plane. This shaft rotation may facilitate the golf club maintaining a substantially constant face angle across a range of soled lie angles. In some aspects, such shaft rotation may enhance the ability of the improved sole geometry to achieve the desired constant face angle result. In other words, the sole geometry and the resulting shaft rotation may work together as an integrated system—the sole geometry may be configured to induce a specific amount of shaft rotation at each soled lie angle such that the face angle remains substantially constant. This relationship between sole geometry and shaft rotation may distinguish the present disclosure from prior approaches that attempt to maintain constant face angle through other means, such as adjustable sole pieces or hosel adjustments, which may not rely on or permit such shaft rotation. The face angle of a soled golf club may be a function of the center of gravity of the entire golf club, including the club head, shaft, and grip. Accordingly, the optimal configuration of the improved region 354 may vary depending on the specific shaft and grip used with the club head 300. In some aspects, the improved region 354 may be configured to provide substantially constant face angle across a range of soled lie angles for a golf club having a shaft and grip with mass properties within predetermined tolerances. For example, the improved region 354 may be configured for use with shafts having a weight within a predetermined range, a length within a predetermined range, and/or a balance point within a predetermined range. Similarly, the improved region 354 may be configured for use with grips having a weight within a predetermined range. In some aspects, a golf club manufacturer may offer multiple club head configurations, each having an improved region 354 optimized for use with shafts and grips having different mass properties. In other aspects, a single improved region 354 configuration may provide acceptable face angle consistency across a range of shaft and grip mass properties, with tighter face angle tolerances achievable when the shaft and grip mass properties are more precisely matched to the assumptions used in designing the improved region 354.

Shown in FIG. 10 is a method 400 of determining a sole geometry that may result in a golf club that maintains a substantially constant face angle over a range of soled lie angles. This method may be executed by a computer system 500, shown in FIG. 11, which may include a processor 510 such as a central processing unit (CPU), a graphics processing unit (GPU), or both. The processor of the computer system 500 may be implemented as a controller, microprocessor, digital signal processor, microcontroller, application specific integrated circuit (ASIC), discrete logic, or a combination of other types of circuits or logic. Moreover, the computer system 500 may include a memory 520 that can communicate via a bus 530 and may store instructions, e.g., software, for execution by the processor 510. The memory 520 may be a main memory, a static memory, or a dynamic memory. The memory 520 may include, but may not be limited to, internal and/or external computer readable storage media such as various types of volatile and non-volatile storage media, e.g., random access memory, read-only memory, programmable read-only memory, electrically programmable read-only memory, electrically erasable read-only memory, flash memory, magnetic tape or disk, optical media, and the like. The memory 520 may include a cache or random access memory for the processor 510. Alternatively or in addition, the memory 520 may be separate from the processor 510 such as a cache memory of a processor, the system memory, or other memory. The computer system 500 may further include a display 550 such as a liquid crystal display (LCD), an organic light emitting diode (OLED), a flat panel display, a solid state display, or a cathode ray tube (CRT). Additionally, the computer system 500 may include an input device 540 such as a keyboard and/or a cursor control device such as a mouse or any other suitable input device.

The method 400 executed by the computer system 500 may begin at Step 410, at which the geometry of the sole portion may be characterized as, say, an ellipsoid. This Step 410 may include identifying the general region of the sole portion that contacts the ground plane across a range of lie angles, sampling many points in this region, e.g., 30, and then performing a least squares fit for an ellipsoid to calculate a set of coefficients. The method may then continue to Step 420, at which an initial soled lie angle, e.g., 40° or 60° is set. From that initial soled lie angle, (i) the center of gravity of the entire club (including club head, shaft, and grip) may be calculated at Step 430, (ii) the contact point(s) at which the sole portion would contact the ground plane may be found at Step 440, and the moment around the shaft axis due to gravity, contact of the sole portion with the ground plane, and pivot at end of the grip may be calculated at Step 450. These steps may include calculating forces due to gravity and friction at the grip pivot and the sole contact point, which are then used to determine the moment about the shaft axis. If that calculated moment about the shaft axis is found to be 0 at Step 460, the method may then proceed to Step 470, at which the face angle of the club head at that orientation may be calculated. But if the calculated moment about the shaft axis is found to be not 0 at Step 460, the virtual golf club may be rotated at Step 465 about its shaft axis and the method may return to Step 430. Once the face angle is calculated at Step 470, the method may then determine at Step 480 whether all soled lie angles have been simulated. If more are to be simulated, the method may return to Step 420, but if no more soled lie angles are to be simulated, the method may proceed to Step 490, at which it may be determined whether a calculated soled lie angle vs. face angle curve (see FIG. 7) meets a predetermined objective. For example, Step 490 may determine whether face angle change remains within 1 degree, 0.5 degree, or 0.2 degree as soled lie angle increases from 40 degrees to 60 degrees. If the predetermined objective is not met at Step 490, the method may return to Step 410, at which a different characterization of the sole geometry may be adopted. This may include modifying the coefficients that define the shape of the improved region, e.g., the ellipsoid. But if the predetermined objective is met at Step 490, the method may end with a manufacturing Step 495, during which a golf club may be manufactured that has the improved sole geometry characterized at Step 410.

In the foregoing discussion, the present invention has been described with reference to specific exemplary aspects thereof. However, it will be evident that various modifications and changes may be made to these exemplary aspects without departing from the broader spirit and scope of the invention. Accordingly, the foregoing discussion and the accompanying drawings are to be regarded as merely illustrative of the present invention rather than as limiting its scope in any manner.

Claims

1. A golf club comprising:

a shaft having a butt end and a tip end; and

a club head including: a volume greater than 360 cubic centimeters; a striking face at a front portion; a rear portion opposite the striking face; a heel portion; a hosel portion shaped to receive therein the tip end of the shaft; a toe portion opposite the heel portion; a crown; and a sole opposite the crown, the sole configured such that: in a first soled position at which the golf club is oriented at a first lie angle between 40 and 60 degrees, the shaft is in a first rotational position and the golf club exhibits a first face angle; in a second soled position at which the golf club is oriented at a second lie angle between 40 and 60 degrees and less than the first lie angle by no less than 1 degree, the shaft is in a second rotational position, which is rotationally offset from the first rotational position in a first direction, and the golf club exhibits a second face angle that is within 1 degree of the first face angle; and in a third soled position at which the golf club is oriented at a third lie angle between 40 and 60 degrees and greater than the first lie angle by no less than 1 degree, the shaft is in a third rotational position, which is rotationally offset from the first rotational position in a second direction opposite the first direction, and the golf club exhibits a third face angle that is within 1 degree of the first face angle.

2. The golf club of claim 1, wherein the second lie angle is less than the first lie angle by no less than 5 degrees, and the third lie angle is greater than the first lie angle by no less than 5 degrees.

3. The golf club of claim 2, wherein, in the second soled position, the shaft is rotationally offset relative the first soled position by at least 1 degree, and in the third soled position, the shaft is rotationally offset relative the first soled position by at least 1 degree.

4. The golf club of claim 2, wherein the second face angle is within 0.5 degrees of the first face angle, and the third face angle is within 0.5 degrees of the first face angle.

5. The golf club of claim 2, wherein the second face angle is within 0.2 degrees of the first face angle, and the third face angle is within 0.2 degrees of the first face angle.

6. The golf club of claim 1,

the sole further comprising an ellipsoid portion having a heel to toe curvature with a first average radius of curvature and a front to rear curvature with a second average radius of curvature, the first average radius of curvature being greater than the second average radius of curvature,

wherein in each of the first soled position, the second soled position, and the third soled position, a ground contact point is located on the ellipsoid portion.

7. The golf club of claim 6, wherein the ellipsoid portion forms less than an entirety of the sole portion and is positioned proximate the striking surface.

8. The golf club of claim 6, further comprising a channel formed in the ellipsoid portion and extending substantially in a heel-to-toe direction.

9. The golf club of claim 1, further comprising a loft less than 13 degrees.

10. A golf club comprising:

a shaft having a butt end and a tip end;

a grip attached to the butt end of the shaft; and

a club head including: a volume greater than 400 cubic centimeters; a striking face at a front portion; a rear portion opposite the striking face; a heel portion; a toe portion opposite the heel portion; a hosel portion shaped to receive therein the tip portion of the shaft; a crown; and a sole opposite the crown, the sole configured such that: in a first soled position at which the golf club is oriented at a first lie angle between 40 and 60 degrees, the shaft is in a first rotational position and the golf club exhibits a first face angle; in a second soled position at which the golf club is oriented at a second lie angle between 40 and 60 degrees and less than the first lie angle by no less than 5 degrees, the shaft is in a second rotational position, which is rotationally offset from the first rotational position in a first direction, and the golf club exhibits a second face angle that is within 0.5 degrees of the first face angle; and in a third soled position at which the golf club is oriented at a third lie angle between 40 and 60 degrees and greater than the first lie angle by no less than 5 degrees, the shaft is in a third rotational position, which is rotationally offset from the first rotational position in a second direction opposite the first direction, and the golf club exhibits a third face angle that is within 0.5 degrees of the first face angle.

11. The golf club of claim 10, wherein, in the second soled position, the shaft is rotationally offset relative the first soled position by more than 1 degree, and in the third soled position, the shaft is rotationally offset relative the first soled position by more than 1 degree.

12. The golf club of claim 10, wherein the second face angle is within 0.2 degrees of the first face angle, and the third face angle is within 0.2 degrees of the first face angle.

13. The golf club of claim 10,

the sole further comprising an ellipsoid portion having a heel to toe curvature with a first average radius of curvature and a front to rear curvature with a second average radius of curvature, the first average radius of curvature being greater than the second average radius of curvature,

wherein in each of the first soled position, the second soled position, and the third soled position, a ground contact point is located on the ellipsoid portion.

14. The golf club of claim 13, wherein the ellipsoid portion forms less than an entirety of the sole portion and is positioned proximate the striking surface.

15. The golf club of claim 13, further comprising a channel formed in the ellipsoid portion and extending substantially in a heel-to-toe direction.

16. The golf club of claim 13, further comprising a loft less than 13 degrees.

17. The golf club of claim 10, wherein the first lie angle is approximately 50 degrees, the second lie angle is approximately 40 degrees, and the third lie angle is approximately 60 degrees.

18. The golf club of claim 17, wherein the second face angle is within 0.2 degrees of the first face angle, and the third face angle is within 0.2 degrees of the first face angle.

19. The golf club of claim 17, wherein, in the second soled position, the shaft is rotationally offset relative the first soled position by at least 2 degrees, and in the third position, the shaft is rotationally offset relative the first soled position by at least 2 degrees.

20. The golf club of claim 10, wherein the first rotational direction is clockwise when the club head is viewed from a top down view along an axis of the shaft and the second rotational direction is counterclockwise when the club head is viewed from the top down view.