Golf Club Head with Optimized Moment of Inertia

This is a continuation of U.S. patent application Ser. No. 18/353,354, filed Jul. 17, 2023, which claims priority to U.S. Provisional Application No. 63/503,134 filed May 18, 2023, U.S. Provisional Application No. 63/370,482 filed Aug. 4, 2022, and U.S. Provisional Application No. 63/368,626 filed Jul. 15, 2022, all of which are incorporated in their entirety.

The present disclosure relates generally to golf equipment, and more particularly, to golf heads. In particular, the present invention is to a golf club head with optimized moments of inertia and/or optimized bulge and roll curvatures.

Historically, golf club head designs, particularly wood-type golf club heads, trend toward increasing club head moment of inertia to offer more forgiveness and minimize decreases in ball speed for mis-hits. Most commonly, prior-art club head designs cater toward increasing Iyy moment of inertia (i.e. the moment of inertia about a Y-axis extending vertically through the club head center of gravity), as Iyy is a main contributor to club head performance and forgiveness, particularly on shots mis-hit toward the heel or the toe. Such club heads are designed to achieve the highest Iyy possible. Prior art club head designs that seek to maximize Iyy often include flat body profiles with high amounts of perimeter weighting that place discretionary mass away from the Y-axis. However, in maximizing Iyy, prior-art club head designs can often neglect other properties, such as Ixx moment inertia (i.e. the moment of inertia about an X-axis extending through the club head center of gravity), or bulge and roll curvatures. An excessively low Ixx and/or bulge and roll curvatures that are not optimized for a given club head can reduce forgiveness and distance on mis-hits, even with a high Iyy.

In certain cases, it may be desirable to provide a wood-type club head that achieves a specific Iyy target value. In many cases, an Iyy target that is lower than the Iyy of a typical prior-art club head may be desired. In some instances, a low Iyy target may be desirable to tailor the club head to a specific player or subset of players. Designing a club head to a low Iyy target, however, can have negative impacts on club head forgiveness and performance, as Iyy is a significant contributor to both. There is a need in the art to maximize club head performance with respect to a club head that achieves a target Iyy. In particular, there is a need in the art to maximize said performance with respect to a club head that achieves a target Iyy lower than the Iyy of a typical prior-art club head, by balancing Ixx, Iyy, CG position, and bulge and roll curvatures.

Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present disclosure. The same reference numerals in different figures denote the same elements.

The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

The terms “couple,” “coupled,” “couples,” “coupling,” and the like should be broadly understood and refer to connecting two or more elements or signals, electrically, mechanically and/or otherwise.

Various embodiments of a golf club are illustrated in the figures. A golf club is generally understood to comprise a club head, which is configured to receive a shaft. A golf club further comprises a grip, which is secured to the shaft.

schematically illustrate various embodiments of a driver-type golf club head in various views. The features discussed below are demonstrated on club head. For ease of discussion, the features shown on club headare applicable to various embodiments of the club head according to the present invention. Any one or more of the features described in the various embodiments below can be used in combination with one another. Further, while different embodiments may comprise different numbering schemes (i.e.,,numbering schemes, etc.) similar elements are numbered similarly between embodiments (i.e. club headcomprises a crownand a sole, whereas club headcomprises a crownand a sole).

The club headcan comprise a strike faceand a bodysecured together to define a substantially closed/hollow interior cavity. The club headcomprises a crown, a soleopposite the crown, a heel, a toeopposite the heel, a front end, and a rear endopposite the front end. The bodycan further include a skirtand/or a trailing edgelocated between and adjoining the crownand the sole. The skirtcan extend from near the heelto near the toeof the club head.

The club headcan comprise one or more body materials such as steel, stainless steel, tungsten, aluminum, titanium, vanadium, chromium, cobalt, nickel, other metals, or metal alloys.

In some embodiments, the body material can comprise a Ti-8Al-1Mo-1V alloy, or a 17-4 stainless steel. In some embodiments, the body material can be formed from C300, C350, Ni (Nickel)-Co (Cobalt)-Cr (Chromium)-Steel Alloy, 565 Steel, AISI type 304 or AISI type 630 stainless steel, 17-4 stainless steel, a titanium alloy, for example, but not limited to Ti-6-4, Ti-3-8-6-4-4, Ti-10-2-3, Ti 15-3-3-3, Ti 15-5-3, Ti185, Ti 6-6-2, Ti-7s, Ti-9s, Ti-92, or Ti-8-1-1 titanium alloy, an amorphous metal alloy, or other similar metals. In some embodiments, one or more portions of the club headcan comprise a non-metallic material.

The “ground plane,” as used herein, refers to a reference plane associated with the surface on which a golf ball is placed. The ground planecan be a horizontal plane tangent to the sole at an address position. Address position is defined in further detail below. The ground planeis illustrated in.

The “loft plane,” as used herein, refers to a reference plane that is tangent to the geometric center of the strike face (the “geometric center” is described in further detail below). Loft planeis illustrated in.

The term “loft angle,” as used herein, can refer to an angle measured between the loft planeand the XY plane (defined below). Loft angleis illustrated in.

The term “lie angle,” as used herein, can refer to an angle between a hosel axis, extending through the hosel, and the ground plane. The lie angleis measured from a front view of the club head, as illustrated in.

The club headcan define an “address position” (also referred to as “address”), wherein the club head is oriented such that club head forms its intended loft angleand lie angle. For example, at address position, the loft planeand the XY plane form the intended loft anglebetween one another. Likewise, at address position, the hosel axisand the ground planeform the intended lie anglebetween one another.

As illustrated in, the club headcan define a primary coordinate system centered about the geometric centerof the strike face. The primary coordinate system can comprise an X-axis, a Y-axis, and a Z-axis. The X-axiscan extend in a heel-to-toe direction, parallel to the ground plane. The X-axiscan be positive towards the heeland negative towards the toe. The Y-axiscan extend in a crown-to-sole direction and can be orthogonal to both the ground planeand the X-axis. The Y-axiscan be positive towards the crownand negative towards the sole. The Z-axiscan extend in front-to-rear direction, parallel to the ground plane, and can be orthogonal to both the X-axisand the Y-axis. The Z-axiscan be positive towards the strike faceand negative towards the rear end.

The primary coordinate system, as described herein, defines an XY plane as a vertical plane extending along the X-axisand the Y-axis. The primary coordinate system defines an XZ plane as a horizontal plane extending along the X-axisand the Z-axis. The primary coordinate system further defines a YZ plane as a vertical plane extending along the Y-axisand the Z-axis. The XY plane, the XZ plane, and the YZ plane are all perpendicular to one another and intersect at the primary coordinate system origin located at the geometric centerof the strike face. In these or other embodiments, the club headcan be viewed from a front view when the strike faceis viewed from a direction perpendicular to the XY plane. Further, in these or other embodiments, the club headcan be viewed from a side view or side cross-sectional view when the heelor toeis viewed from a direction perpendicular to the YZ plane.

The “body depth,” or “depth” Dof the club head, as used herein, refers to a front-to-rear dimension measured across the body. Referring to, the body depth Dis measured parallel to the Z-axisfrom the leading edgeto the rearward-most pointof the body.

The “body height,” or “height” Hof the club head, as described herein, can refer to a crown-to-sole dimension measured across the body. Referring to, the body height Hcan be measured as a vertical distance (parallel to the Y-axis) between the ground planeand the highest point of the crown. In many embodiments, the body height Hcan be measured according to a golf governing body such as the United States Golf Association (USGA).

The “body width,” or “width” Wof the club head, as described herein, can refer to a heel-to-toe dimension measured across the body. Referring to, the body width Wcan be measured parallel to the X-axisfrom the heel apexto a toe apex. The toe apexis defined as the toeward-most point of the body. The heel apexis heelward-most point of the heelthat is located at a height 0.875 mm from the ground plane. In many embodiments, the body width Wcan be measured according to a golf governing body such as the United States Golf Association (USGA). The ranges specified for the body depth D, body height H, and body width Wcan be designed in accordance with the USGA regulations.

The “center of gravity” or “CG” of the club head, as described herein, can refer to the point at which the mass is centered within the club head. The CGis illustrated in.

The term or phrase “center of gravity position” or “CG location” can refer to the location of the club head center of gravity (CG) with respect to the primary coordinate system, wherein the CG position is characterized by locations along the X-axis, the Y-axis, and the Z-axis. The term “CGx” can refer to the CG location along the X-axis, measured from the geometric center. The term “CG height” can refer to the CG location along the Y-axis, measured from the geometric center. The term “CGy” can be synonymous with the CG height. The term “CG depth” can refer to the CG location along the Z-axis, measured from the geometric center. The term “CGz” can be synonymous with the CG depth.

The golf club head further comprises a secondary coordinate system centered about the center of gravity. As illustrated in, the secondary coordinate system comprises an X′-axis, a Y′-axis, and a Z′-axis. The X′-axisextends in a heel-to-toe direction. The X′-axisis positive towards the heeland negative towards the toe. The Y′-axisextends in a sole-to-crown direction and is orthogonal to both the Z′-axisand the X′-axis. The Y′-axisis positive towards the crownand negative towards the sole. The Z′-axisextends front-to-rear, parallel to the ground planeand is orthogonal to both the X′-axisand the Y′-axis. The Z′-axisis positive towards the strike faceand negative towards the rear end.

The term or phrase “moment of inertia” (hereafter “MOI”) can refer to a value derived using the center of gravity (CG) location. The term “MOI” or “I” can refer to the MOI measured about the X′-axis. The term “MOIyy” or “I” can refer to the MOI measured about the Y′-axis. The term “MOIzz” or “I” can refer to the MOI measured about the Z′-axis. The MOI values MOIxx, MOIyy, and MOIzz determine how forgiving the club headis for off-center impacts with a golf ball.

MOI is a measurement of an object's resistance to twisting about a given axis and is calculated according to Equation 1 below.

Equation 1 defines MOI, represented by I, of an object as the integral, with respect to mass (represented by dm), of the perpendicular distance between the axis about which MOI is being measured and the location of the mass of the object, represented by r, squared. It is generally known that, if the center of gravity (CG) of an object is known, that object may be treated as a point mass located at said CG. Treating an object as a point mass allows Equation 1 to be simplified to the following equation, Equation 2.

Equation 2 describes that the moment of inertia, I, of an object about a given axis is equal to the sum of the masses of all point masses of that object multiplied by the perpendicular distance between the axis about which MOI is being measured and each of the point masses.

The term “strike face,” as used herein, refers to a club head front surface that is configured to strike a golf ball. The term strike face can be used interchangeably with the term “face.”

The term “strike face perimeter,” as used herein, can refer to an edge of the strike face. The strike face perimeter can be located along an outer edge of the strike face where the curvature of the club head deviates from a bulge and/or roll curvature of the strike face (defined below). Referring to, the strike face perimeter includes an upper edge, which defines a highest point on the strike face. The strike face perimeter further includes a leading edge, which defines a lowest point on the strike face. The strike face perimeter is the outermost bound of the strike face.

The “leading edge” of the club head, as described herein, can be identified as the most sole-ward portion of the strike face perimeter. For example, as illustrated in, the leading edgeis the transition from the strike faceto the soleof the club head.

The “strike face height” Hof the club head, as used herein, refers to a distance measured from the lowest point of the strike face perimeter to the highest point of the strike face perimeter. Referring to, the height Hcan be measured parallel to the loft plane, from the leading edgeto the upper edgeof the strike face, wherein the upper edgerepresents the most crown-ward portion of the strike faceperimeter.

The “strike face width” Wof the club head, as used herein, refers to a horizontal distance measured across the strike face in a heel-to-toe direction. Referring to, the strike face width Wcan be measured parallel to the ground plane, from a heel-most extent of the strike face perimeter to a toe-most extent of the strike face perimeter.

The “geometric center” of the strike face, as used herein, refers to a geometric centerpoint of the strike face perimeter, illustrated in. The geometric centerpointof the strike facecan be located in accordance with the definition of a golf governing body such as the United States Golf Association (USGA).

As illustrated in, the strike facecomprises a geometric center height H. The geometric center height His measured from the leading edgeto the geometric center, parallel to the loft plane.

The strike face comprises a “bulge curvature”, and a “roll curvature”. The bulge curvature is the curvature of the strike face in the heel-to-toe direction. The roll curvature is the curvature of the strike face in a crown-to-sole direction. The bulge curvature and the roll curvature each respectively comprise a “bulge radius” and a “roll radius” defining the radii of curvature associated with each of the bulge curvature and the roll curvature. The bulge curvature and/or the roll curvature can comprise one or more radii.

As illustrated in, the club headfurther comprises a force lineintersecting the geometric centerand extending parallel to the loft plane. The launch characteristics of a golf ball are dependent on the relationship between the force lineand the CG. The closer the CGis to the force line, the greater the energy transfer between the club headand the golf ball at impact. The launch characteristics of the club headat impact remain substantially consistent as long as the distance between the CGand the force lineis constant, even if the CGmoves relative to the rest of the club head.

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.

The golf club head described herein comprises various features and characteristics to maximize performance in view of a specific moment of inertia target value. In particular, the club head described below may be designed to achieve a particular Iyy target value and maximize performance and forgiveness relative to the limits of said Iyy target. In general, a higher Iyy provides a more forgiving club head. A club head with a higher Iyy has a greater resistance to rotation at impact for shots that are heelward or toeward of center. A higher Iyy club head also retains more energy at impact on a heelward or toeward mis-hit. Therefore, a higher Iyy club head generally provides greater ball speeds and distances on heelward or toeward mis-hits. However, there are other contributing factors to club head forgiveness and overall performance, such as the Ixx moment of inertia and bulge and roll curvatures. The embodiments described herein provide features and characteristics that increase Ixx relative to the Iyy target. The embodiments described herein further comprise optimized bulge and roll curvatures determined by the Iyy target combined with other club head properties (i.e. Ixx, CG position, coefficient of restitution, etc.) Increasing the Ixx can provide increased forgiveness and distance on crown-ward or sole-ward mis-hits. Optimizing the bulge and roll curvatures can further increase forgiveness in distance by counteracting the gearing effect imparted on the golf ball on an off-center strike. In particular, the embodiments described herein are directed to driver-type golf club heads (designed to be primarily used to hit a golf ball off of a tee) comprising a specific Iyy target value. The present embodiments are not directed to fairway wood-type, hybrid-type, or iron-type club heads. Although the driver-type club heads described herein are intended to hit a golf ball off of a tee, said club heads may also be suitable for hitting the golf ball off of the ground.

As described above, there are two main club head characteristics that provide improved performance relative to a fixed Iyy target: 1) Ixx moment of inertia and 2) bulge and roll curvatures. The club head of the present disclosure provides a high Ixx moment of inertia relative to the Iyy target. In many embodiments, the club head can comprise an Ixx/Iyy ratio greater than 0.80. Providing a high Ixx relative to the Iyy target increases the overall forgiveness of the club head. Ixx represents the club head's resistance to rotation about the X′-axis on golf shots that are struck above or below center. As described in the definitions above, the X′-axis is a heel-to-toe axis with respect to a coordinate system centered about the club head CG. The X′-axis extends horizontally through the CG in a heel-to-toe direction. In particular, a higher Ixx/Iyy ratio provides a club head with increased resistance to rotation about the X′-axis at impact for shots that are crownward or soleward of center. Increasing the Ixx/Iyy ratio reduces the effect of the club head rotation about the X′-axis and balances the backspin on the golf ball, thereby increasing golf shot distance on crown-ward or sole-ward mis-hits.

The present club head maximizes the Ixx/Iyy ratio through “cube-like” shaping and distributing a large portion of the club head mass near the Y′-axis. The club head comprises a cube-like profile wherein the body width, body height, and body depth are more similar to one another than the width, height, and depth of a prior art club head. The cube-like profile of the club head spaces the mass of the crown and the sole away from the X′-axis, thereby increasing Ixx without contributing to Iyy. Most prior art club heads, particularly modern club heads comprise a flatter, wider, and deeper profile, wherein the body height is significantly smaller than the body width or body depth. Such prior-art club heads give preference to increasing Iyy without regard for Ixx. These prior art club head shapes efficiently increase Iyy, by spacing club head mass away from the Y′-axis via shaping. However, such designs do not prioritize the amount of structural mass away from the X′-axis, and therefore the Ixx/Iyy ratio is not maximized.

To maximize the Ixx/Iyy ratio, the present club head efficiently distributes mass to contribute to Ixx without contributing to Iyy. The club head can distribute a large proportion of mass near the Y′-axis, yet far from the X′-axis. To achieve this mass distribution, the club head can comprise one or more weighting features such as internal mass pads or removable weights located near the the Y′-axis and far from the X′-axis. Any such features can serve to provide a significant increase in Ixx relative to Iyy, thereby providing an increased Ixx/Iyy ratio.

The club head can further comprise a strike face with optimized bulge and roll curvatures to increase performance and forgiveness. The bulge and roll curvatures can be specifically tailored to a specific club head based on properties of said club head, including Ixx, Iyy, CG position, coefficient of restitution, and/or other club head characteristics. The present club head can satisfy one or more bulge radius or roll radius relationships to maximize distance and forgiveness. The bulge and roll radii of the present club head counteract the gearing effect imparted on the golf ball on an off-center strike. Providing bulge and roll radii as a function of the club head characteristics can increase forgiveness and distance to provide a higher-performing club head, even in cases where the Iyy target is substantially low. In embodiments wherein the Iyy target is substantially low, the optimized bulge and roll radii can compensate for losses in forgiveness and ball speed associated with the low Iyy target.

In many embodiments, the club head can further comprise an adjustable swing weight system that provides a plurality of available club head builds at a consistent Iyy target. The adjustable swing weight system includes a plurality of interchangeable and/or removable weight inserts that are each configured to provide a consistent Iyy contribution. The adjustable swing weight system provides the ability to vary the total club head mass by more than 25 grams while keeping Iyy consistent between different builds.

As described above, the club head of the present invention is designed to achieve a designated target value for Iyy moment of inertia (hereafter “Iyy target”). In some embodiments, the Iyy target value can coincide substantially with the moment of inertia limits imposed by the USGA with respect to a conforming club head. In many embodiments, however, the Iyy target value can be lower than the USGA limit. Club heads designed to achieve an Iyy target at or near the USGA limit can be referred to herein as “high-MOI” club heads, whereas club heads designed to achieve an Iyy target significantly lower than the USGA limit can be referred to herein as “low-MOI”club heads. The embodiments and examples herein are primarily directed to low-MOI club heads, however any combination of the principles, properties, features, elements, or methods disclosed below can be applicable to high-MOI club heads as well. Unless otherwise specified, the mass properties described herein, including moment of inertia values and CG positions, reflect a “fully built” club head. A fully built club head includes all applicable weight inserts, removable weights, permanent weights, swing weights, filler material, and/or any other removable components such as those associated with an adjustable hosel assembly.