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Golf club head and method of varying moment of inertia of same

Golf club head and method of varying moment of inertia of same description/claims

The present invention relates to golf club heads, and more specifically, to optimizing the moment of inertia of driver golf club heads and a method for manipulating the mass characteristics of golf club heads.

Manipulation of mass distribution in golf club heads can improve club head characteristics such as center of gravity and moment of inertia. Driver club heads typically consist of a crown, a sole, a skirt disposed in between the crown and sole and a hitting face. Changes in the distribution of weight between these portions of the club head vary the center of gravity or moment of inertia of the club head, and thus produce changes in the characteristics of the impact between the club head and a golf ball and the flight path of the golf ball.

Golfers of all skill levels may benefit from using golf clubs having high moments of inertia, as the moment of inertia of a golf club head influences the degree to which an off-center hit will send a golf ball off of its intended trajectory. Hooks and slices are produced when a golf club head makes contact with a golf ball at a location off to the side of the center of gravity of the club head, imparting side-spin to the golf ball and causing it to veer off of its intended path. Golfers who have difficulty connecting the golf club head with the golf ball at the sweet spot would benefit from using a golf club head that has a high moment of inertia. The greater the moment of inertia of the club head, the more resistant the club head will be to undesired rotational movement about the axis that runs vertically through the center of gravity of the golf club head, referred to hereinafter as the z-axis. The less the club head moves about the z-axis as it makes contact with the golf ball, the less side-spin it will impart to the golf ball. This would, in turn, mitigate the severity of the hook or slice.

Golfers who are able to exercise great control over the location of the impact between the club head and the golf ball often use this skill to their advantage by intentionally imparting spin to the golf ball. These skilled players can achieve added control over the movement of the golf ball by using golf clubs with improved moments of inertia.

A number of methods have been developed to produce golf club heads with mass distributions that improve mass characteristics of the club heads. One method, disclosed in U.S. Pat. No. 6,386,990, is to include pieces of weighted material in the body of the club head. The '990 patent discloses a golf club head consisting of a face, a sole, a crown and a skirt disposed in between the crown and sole made of a composite material. A strip of material having a greater density than the composite material is disposed to the skirt of the club head. In another example, U.S. Pat. No. 7,147,573 discloses a golf club head with a recess extending through the body of the club head in an arc-like shape from the heel end to the toe end. Within this recess is a cable, attached to which is at least one weight member that may be moved to vary the mass characteristics of the club head.

Another method of manipulating mass characteristics is to construct a golf club head having components of different materials. For example, U.S. Pat. No. 7,144,336 discloses a golf club head composed of a periphery member, comprising a sole wall, a toe wall, a hosel and a heel wall; a central member, comprising a body with forward, rear, sole, top, toe and heel surfaces; and a face plate. The periphery member is made of a high density metal material such as nickel-tungsten alloy, the central member is composed of a lightweight, non-metal material, and the face plate is composed of a lightweight metal material such as titanium alloy.

Another attempt to manipulate mass characteristics involves changing the shape of the golf club head. For instance, U.S. Pat. No. 7,077,758 discloses a putter having an arrangement of components wherein the majority of the mass is situated within three or more separate positions that are approximately equidistant from the center of mass of the club head. These three positions lie inside a “mass ring”, the outside diameter of which is approximately the same length as the distance between the ends of the putter striking face.

These examples of the prior art describe ways to vary the mass characteristics of golf club heads, however they do not disclose a method applicable to a broad range of styles of golf club heads for optimizing mass characteristics, specifically moment of inertia. Hence, a need exists in the art for a golf club head having an optimized moment of inertia. There is also a need for a method of determining how to optimize the mass characteristics of a golf club head.

The present invention is directed to a golf club head with an optimized moment of inertia (MOI).

The present invention is also directed to a method of controlling mass characteristics of golf club heads.

The present invention is preferably directed to a golf club head having a crown, face, skirt and sole, such that the distribution of mass in the sole affects the moment of inertia of the club head. In one embodiment of the present invention, the mass of the sole is allocated relative to the location of a centroid radius of the sole. When more of the sole's mass is allocated outside of the centroid radius of the sole, the moment of inertia of the sole is increased. By extension, the moment of inertia of the entire club head, when all other mass characteristics of the crown, face, and skirt remain constant, is increased.

A method for determining the centroid radius is also disclosed. In accordance with this aspect of the present invention, the centroid radius is defined as the distance located on the sole and radially away from a reference point on the sole through which an axis of rotation runs, at which the moment of inertia (MOI) of the sole would change from a reduction relative to a designated baseline MOI to an increase relative to the designated baseline MOI when more of the sole's mass is located beyond that centroid radius. The reference point can also coincide with the hosel, a center of gravity of the club head or a center of gravity of the club head.

In another embodiment of the present invention, a method of optimizing the MOI of a golf club head sole is presented. Mass is distributed in an arc-like pattern on the sole, said arcs radiating away from a reference location that coincides with the axis of rotation of the club head, said axis can be as the shaft of the club, to determine the location on the sole where mass reallocation results in greater MOI than a baseline MOI calculated in regard to a sole having uniform density, thickness and mass distribution.

Yet another embodiment of the present invention discloses a method of optimizing mass distribution to balance the center of gravity of the club head and MOI. Due to the concavity of the sole, center of gravity will shift upward and rearward as more mass is moved radially outward to increase MOI. A balance between these factors can be obtained to maximize mass properties or to individually customize clubs.

In other embodiments of the present invention, a golf club head is presented having a sole composed of areas of various materials, said areas being located relative to a centroid radius in order to optimize MOI of the club head.

FIG. 1 is a bottom perspective view of a golf club head having a sole with areas of varying mass distribution according to the present invention;

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