GOLF CLUB HEAD

Abstract

A head 2 includes a head body h1 and at least one weight . The head body h1 includes a face 10, an upper-side weight-disposal part Wa positioned on an upper side of a center of gravity HG of the head body h1, and a lower-side weight-disposal part Wb positioned on a lower side of the center of gravity HG of the head body h1. At least one of the upper-side weight-disposal part Wa and the lower-side weight-disposal part Wb is configured to change mass distribution in a toe-heel direction. The upper-side weight-disposal part Wa may be constituted of a first weight port WP1 and a second weight port WP2. The lower-side weight-disposal part Wb may be constituted of a third weight port WP3 and a fourth weight port WP4.

Description

The present application claims priority on Patent Application No. 2015-61180 filed in JAPAN on Mar. 24, 2015, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a golf club head.

2. Description of the Related Art

A golf club having excellent flight distance performance has been desired. As means for improving the flight distance performance, there have been known the increase in the coefficient of restitution of a face, the increase in the mass of a head, the increase in the length of a club, and the adjustment of the position of the center of gravity of the head, or the like (see the following Patent Literatures 1 to 3).

Meanwhile, the increase in an average flight distance has been attempted in consideration of the variation in golfer's hitting points (see the following Patent Literature 4).

Patent Literature 1: U.S. Patent Application Publication No. 2013/0109501

Patent Literature 2: U.S. Patent Application Publication No. 2013/0324299

Patent Literature 3: U.S. Patent Application Publication No. 2014/0106901

Patent Literature 4: Japanese Patent No. 3,063,967 (USP5,836,830)

SUMMARY OF THE INVENTION

There is a limit on the increase in the coefficient of restitution of a face due to the regulation of the rules . There is a limit on the increase in the mass of a head and the increase in the length of a club from the viewpoint of the easiness of swing. There is a limit on the freedom degree of design of the center of gravity of the head from the restriction of the volume of the head or the like.

A principal axis of inertia is considered in Japanese Patent No. 3,063,967. This is effective in the increase in an average flight distance, and there is still potential for improvement. The present inventor completed a new invention for mass distribution capable of improving the flight distance performance of a head.

It is an object of the present invention to provide a golf club head capable of exhibiting excellent flight distance performance for each golfer.

A preferable golf club head includes a head body and at least one weight. The head body includes a face, an upper-side weight-disposal part positioned on an upper side of a center of gravity of the head body, and a lower-side weight-disposal part positioned on a lower side of the center of gravity of the head body. At least one of the upper-side weight-disposal part and the lower-side weight-disposal part is configured to change mass distribution in a toe-heel direction.

Preferably, the upper-side weight-disposal part is constituted of a first weight port and a second weight port. Preferably, the lower-side weight-disposal part is constituted of a third weight port and a fourth weight port.

The center of gravity of the head body is defined as an origin in a base state where the head is disposed on a level surface at a predetermined lie angle and loft angle; a straight line in the toe-heel direction passing through the origin is defined as an x-axis; a straight line in a vertical direction passing through the origin is defined as a y-axis; and a plane parallel to the x-axis and the y-axis is defined as an xy plane. Preferably, in the head, a specific xy plane satisfying all of the following (a) to (d) exists:

(a) a distance between the specific xy plane and the first weight port is equal to or less than 20 mm;

(b) a distance between the specific xy plane and the second weight port is equal to or less than 20 mm;

(c) a distance between the specific xy plane and the third weight port is equal to or less than 20 mm; and

(d) a distance between the specific xy plane and the fourth weight port is equal to or less than 20 mm.

An xy coordinate system is constituted of the x-axis and the y-axis in planar view from a face side. Preferably, in the planar view, the first weight port is positioned in a first quadrant of the xy coordinate system; the second weight port is positioned in a second quadrant of the xy coordinate system; the third weight port is positioned in a third quadrant of the xy coordinate system; and the fourth weight port is positioned in a fourth quadrant of the xy coordinate system.

Of three principal axes of inertia orthogonal to each other, a principal axis of inertia having the smallest angle with respect to the y-axis is projected on the xy plane to obtain a straight line. The straight line is defined as a base line, and the angle between the base line and the y-axis is defined as an inclination of the principal axis of inertia.

A height of a center of gravity of the head is defined as Gy, and a position of the center of gravity of the head in the toe-heel direction is defined as Gx. Preferably, the head is configured to change the inclination of the principal axis of inertia without changing the height Gy and the position Gx.

A height of a center of gravity of the head is defined as Gy and a position of the center of gravity of the head in the toe-heel direction is defined as Gx. Preferably, the head is configured to change the position Gx without changing the height Gy. Preferably, the head is configured to change the position Gy without changing the position Gx.

Preferably, an adjustable range of the height Gy is 1 mm or greater and 10 mm or less under a condition where a mass of the head is constant.

Preferably, an adjustable range of the position Gx is 1 mm or greater and 15 mm or less under a condition where a mass of the head is constant.

Preferably, an adjustable range of the inclination of the principal axis of inertia is 1 degree or greater and 20 degrees or less under a condition where a mass of the head is constant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a golf club head according to a first embodiment;

FIG. 2 is a top view of the head of FIG. 1, and two weight ports are simplified in FIG. 2;

FIG. 3 is a bottom view of the head of FIG. 1, and weights are omitted in FIG. 3;

FIG. 4 is a front view showing the inside of the head of FIG. 1;

FIG. 5 is a perspective view of the head of FIG. 1 viewed from a sole side;

FIG. 6 is a top view of a head according to a second embodiment, and the positions of two weight ports are represented by hatching in FIG. 6;

FIG. 7 is a bottom view of the head according to the second embodiment, and the positions of two weight ports are represented by hatching in FIG. 7;

FIG. 8 is a top view of a head according to a third embodiment;

FIG. 9 is a bottom view of the head according to a third embodiment, and the positions of four weight ports are represented by hatching in FIG. 9;

FIG. 10 is a side view of the head according to the third embodiment, and the position of one weight port is represented by hatching in FIG. 10;

FIG. 11 is a top view of a head according to a fourth embodiment, and the positions of two weight ports are represented by hatching in FIG. 11;

FIG. 12 is a bottom view of the head according to the fourth embodiment;

FIG. 13 is a top view of a head according to a fifth embodiment, and the position of one weight port is represented by hatching in FIG. 13;

FIG. 14 is a bottom view of the head according to the fifth embodiment;

FIG. 15 is a top view of a head according to a sixth embodiment, and the positions of two weight ports are represented by hatching in FIG. 15; and

FIG. 16 is a bottom view of the head according to the sixth embodiment, and the positions of two weight ports are represented by hatching in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described below in detail based on preferred embodiments with appropriate reference to the drawings.

FIG. 1 is a front view of a golf club head 2 (head body h1) according to a first embodiment of the present invention. FIG. 2 is a top view of the head 2. FIG. 3 is a bottom view of the head 2. In a sole of FIG. 3, members other than two weight ports are omitted. The sole of the head 2 are shown in detail in FIG. 5 to be described later.

The head 2 is a wood type head. The head 2 is a so-called driver head. The head 2 may be a utility type (hybrid type) head. The head 2 may be an iron type head. The head 2 may be a putter type head.

The head 2 includes the head body h1 and a weight. The number of weights may be 1, or equal to or greater than 2. In FIG. 2, the weights are simplified as a simple cylinder. The weights are omitted in FIG. 3. These weights will be described in detail later.

The head body h1 includes a crown 4, a sole 6, a hosel 8, and a face 10. The crown 4 extends toward the back side of the head from the upper edge of the face 10. The sole 6 extends toward the back side of the head from the lower edge of the face 10. The outer surface of the face 10 is a hitting surface. The hitting surface is also referred to as a face surface. As shown in FIG. 2, the hosel 8 has a hosel hole 12.

Furthermore, the head body h1 includes a side part 14. The side part 14 extends between the crown 4 and the sole 6. The side part 14 is also referred to as a skirt. The side part 14 may not exist.

The inside of the head body h1 is a space. In other words, the head body hl is hollow.

[Definitions of Terms]

The following terms are defined in the present application.

[Base State and Base Perpendicular Plane]

A base perpendicular plane perpendicular to a level surface H is set (abbreviated in the drawings). A state where a center axis line Z1 of a shaft hole of a head is included in the base perpendicular plane and the head is placed at a specified lie angle and real loft angle on the level surface H is defined as abase state (abbreviated in the drawings). The specified lie angle and real loft angle are described in, for example, a product catalog.

[Toe-Heel Direction]

A toe-heel direction is a direction of an intersection line between the base perpendicular plane and the level surface H.

[Face-Back Direction]

A face-back direction is a direction perpendicular to the toe-heel direction and parallel to the level surface H.

[Vertical Direction]

A vertical direction is a direction perpendicular to the level surface H.

[Center of Gravity HG of Head Body]

A head body in the present application means a portion excluding a detachably attached weight. Therefore, the center of gravity HG of the head body is a center of gravity in a state where all detachably attached weight(s) are detached.

[Center of Gravity of Head]

The center of gravity of a head is a center of gravity in a state where all detachably attached weight(s) are attached to the head. Therefore, the center of gravity of the head does not necessarily coincide with the center of gravity HG of the head body.

[X-Axis]

A straight line passing through the center of gravity HG of the head body and being parallel to the toe-heel direction is defined as an x-axis. An x-coordinate is zero in the center of gravity HG, with a heel side as a plus and a toe side as a minus.

[Y-Axis]

A straight line passing through the center of gravity HG of the head body and being parallel to the vertical direction is defined as a y-axis. A y coordinate is zero in the center of gravity HG, with an upper side as a plus and a lower side as a minus. The y-axis is perpendicular to the x-axis.

[Z-Axis]

A straight line passing through the center of gravity HG of the head body and being parallel to the face-back direction is defined as a z-axis. A z coordinate is zero in the center of gravity HG, with a back side as a plus and a face side as a minus. The z-axis is perpendicular to the x-axis and the y-axis.

[XY Plane]

A plane parallel to the x-axis and the y-axis is an xy plane . The z coordinate of the xy plane is not limited. Innumerable xy planes exist.

[Specific XY Plane]

A specific xy plane is one xy plane selected from the innumerable xy planes which may exist. The z coordinate of the specific xy plane is not limited.

[Planar View]

A projection image projected on the xy plane from the face side is planar view. The direction of the projection is a direction perpendicular to the xy plane. FIG. 4 shows an example of the planar view.

[XY Coordinate System]

A plane coordinate system obtained by projecting the x-axis and the y-axis on the xy plane is an xy coordinate system. The direction of the projection is a direction perpendicular to the xy plane.

FIG. 4 is a front view showing the inside of the head 2 (head body h1). In order to show the inside of the head 2, a part of the face 10 is removed in FIG. 4. The head body h1 includes a first weight port WP1, a second weight port WP2, a third weight port WP3, and a fourth weight port WP4. Other weight ports may be further provided.

A weight may be disposed in the weight port. The weight may be detachably attached to the weight port. The weight may be detachably attached to each of the weight ports WP1, WP2, WP3, and WP4.

The first weight port WP1 is provided in the crown 4. The second weight port WP2 is provided in the crown 4. The first weight port WP1 is provided on a heel side with respect to the second weight port WP2. The first weight port WP1 is provided on an upper side of the center of gravity HG of the head body h1. The second weight port WP2 is provided on an upper side of the center of gravity HG. The first weight port WP1 is provided on a heel side with respect to the center of gravity HG. The second weight port WP2 is provided on a toe side with respect to the center of gravity HG.

The position of the first weight port WP1 in the x-axis direction is different from the position of the second weight port WP2 in the x-axis direction. In other words, the position of the first weight port WP1 in the toe-heel direction is different from the position of the second weight port WP2 in the toe-heel direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The position of the first weight port WP1 in the y-axis direction may be different from the position of the second weight port WP2 in the y-axis direction. In other words, the position of the first weight port WP1 in the vertical direction may be different from the position of the second weight port WP2 in the vertical direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The position of the first weight port WP1 in the z-axis direction may be different from the position of the second weight port WP2 in the z-axis direction. In other words, the position of the first weight port WP1 in the face-back direction may be different from the position of the second weight port WP2 in the face-back direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The third weight port WP3 is provided in the sole 6. The fourth weight port WP4 is provided in the sole 6. The fourth weight port WP4 is provided on a heel side with respect to the third weight port WP3. The third weight port WP3 is provided on a lower side of the center of gravity HG of the head body h1. The fourth weight port WP4 is provided on a lower side of the center of gravity HG. The third weight port WP3 is provided on a toe side with respect to the center of gravity HG. The fourth weight port WP4 is provided on a heel side with respect to the center of gravity HG.

The position of the third weight port WP3 in the x-axis direction is different from the position of the fourth weight port WP4 in the x-axis direction. In other words, the position of the third weight port WP3 in the toe-heel direction is different from the position of the fourth weight port WP4 in the toe-heel direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The position of the third weight port WP3 in the y-axis direction may be different from the position of the fourth weight port WP4 in the y-axis direction. In other words, the position of the third weight port WP3 in the vertical direction may be different from the position of the fourth weight port WP4 in the vertical direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The position of the third weight port WP3 in the z-axis direction may be different from the position of the fourth weight port WP4 in the z-axis direction. In other words, the position of the third weight port WP3 in the face-back direction may be different from the position of the fourth weight port WP4 in the face-back direction. The position difference can improve the freedom degree of the adjustment of the center of gravity of the head.

The first weight port WP1 is provided on a back side with respect to the center of gravity HG. The second weight port WP2 is provided on a back side with respect to the center of gravity HG. The third weight port WP3 is provided on a back side with respect to the center of gravity HG. The fourth weight port WP4 is provided on a back side with respect to the center of gravity HG.

The first weight port WP1 may be provided on a face side with respect to the center of gravity HG. The second weight port WP2 maybe provided on a face side with respect to the center of gravity HG. The third weight port WP3 may be provided on a face side with respect to the center of gravity HG. The fourth weight port WP4 may be provided on a face side with respect to the center of gravity HG.

The head body h1 includes an upper-side weight-disposal part Wa positioned on an upper side of the center of gravity HG of the head body h1. In the present embodiment, the upper-side weight-disposal part Wa is constituted of the first weight port WP1 and the second weight port WP2. The upper-side weight-disposal part Wa is configured to change mass distribution in the toe-heel direction. By changing the mass distribution of the weight disposed in the first weight port WP1 and the weight disposed in the second weight port WP2, the mass distribution in the toe-heel direction can be changed.

The head body h1 includes a lower-side weight-disposal part Wb positioned on a lower side of the center of gravity HG of the head body h1. In the present embodiment, the lower-side weight-disposal part Wb is constituted of the third weight port WP3 and the fourth weight port WP4. The lower-side weight-disposal part Wb is configured to change mass distribution in the toe-heel direction. By changing the mass distribution of the weight disposed in the third weight port WP3 and the weight disposed in the fourth weight port WP4, the mass distribution in the toe-heel direction can be changed.

Thus, in the present embodiment, both the upper-side weight-disposal part Wa and the lower-side weight-disposal part Wb allow mass transfer in the toe-heel direction. Either the upper-side weight-disposal part Wa or the lower-side weight-disposal part Wb may allow the mass transfer in the toe-heel direction.

FIG. 4 is also planar view from the face side. All structures included in the head body h1 (head 2) are assumed to be projected in the planar view. Therefore, the inside structure of the head 2 is also reflected in the planar view. The xy coordinate system is constituted in the planar view. A two-dot chain line Lx in FIG. 4 is an x-axis of the xy coordinate system. A two-dot chain line Ly in FIG. 4 is a y-axis of the xy coordinate system.

As shown in FIG. 4, the first weight port WP1 is positioned in a first quadrant Q1 of the xy coordinate system. The second weight port WP2 is positioned in a second quadrant Q2 of the xy coordinate system. The third weight port WP3 is positioned in a third quadrant Q3 of the xy coordinate system. The fourth weight port WP4 is positioned in a fourth quadrant Q4 of the xy coordinate system.

Thus, the first to fourth weight ports are respectively distributed to the first quadrant Q1, the second quadrant Q2, the third quadrant Q3, and the fourth quadrant Q4. By the distribution, the adjustment of the center of gravity of the head can be realized with a high freedom degree. By the distribution, the adjustment of the inclination of a principal axis of inertia can be realized with a high freedom degree.

A recess in which the weight is disposed is usually provided in the weight port. The position of the weight port can be assumed to be the position of the center of gravity of a substance having a constant specific gravity when the recess formed in the weight port is filled with the substance. The position of the center of gravity of the filled substance is usually substantially equal to the position of the center of gravity of the weight mounted in the weight port. For example, the position of the weight port can be assumed to be the position of the center of gravity of the weight when a stainless steel weight of 4 g is attached to the weight port.

As shown in FIG. 2, a specific xy plane SP1 satisfying all of the following (a) to (d) exists in the head 2. In FIG. 2, the specific xy plane SP1 is represented by one straight line (two-dot chain line):

(a) a distance between the specific xy plane SP1 and the first weight port WP1 is equal to or less than 20 mm;

(b) a distance between the specific xy plane SP1 and the second weight port WP2 is equal to or less than 20 mm;

(c) a distance between the specific xy plane SP1 and the third weight port WP3 is equal to or less than 20 mm; and

(d) a distance between the specific xy plane SP1 and the fourth weight port WP4 is equal to or less than 20 mm.

In the head 2 satisfying the above (a) to (d), the positions of the four weight ports in the face-back direction are close to each other. Therefore, the mass distribution can be changed while the movement of the center of gravity of the head in the face-back direction is suppressed. For example, the position of a sweet spot can be changed while the variation in the depth of the center of gravity is suppressed. For example, the inclination of the principal axis of inertia can be changed without substantially moving the position of the center of gravity of the head in the face-back direction.

In the present embodiment, a number of specific xy planes SP1 exist. The specific xy plane SP1 is selected from a number of xy planes. In FIG. 2, a plane SP11 and a plane SP12 are shown as the specific xy plane SP1, but these are two examples of a number of specific xy planes SP1.

From the above-mentioned viewpoint, a specific xy plane SP1 satisfying all of the following (a1) to (d1) more preferably exists:

(a1) a distance between the specific xy plane SP1 and the first weight port WP1 is equal to or less than 15 mm;

(b1) a distance between the specific xy plane SP1 and the second weight port WP2 is equal to or less than 15 mm;

(c1) a distance between the specific xy plane SP1 and the third weight port WP3 is equal to or less than 15 mm; and

(d1) a distance between the specific xy plane SP1 and the fourth weight port WP4 is equal to or less than 15 mm.

From the above-mentioned viewpoint, a specific xy plane SP1 satisfying all of the following (a2) to (d2) more preferably exists:

(a2) a distance between the specific xy plane SP1 and the first weight port WP1 is equal to or less than 10 mm;

(b2) a distance between the specific xy plane SP1 and the second weight port WP2 is equal to or less than 10 mm;

(c2) a distance between the specific xy plane SP1 and the third weight port WP3 is equal to or less than 10 mm; and

(d2) a distance between the specific xy plane SP1 and the fourth weight port WP4 is equal to or less than 10 mm.

The specific xy plane SP12 (see FIG. 2) satisfies all of the following (a3) to (d3):

(a3) a distance between the specific xy plane SP12 and the first weight port WP1 is equal to or less than 3 mm;

(b3) a distance between the specific xy plane SP12 and the second weight port WP2 is equal to or less than 3 mm;

(c3) a distance between the specific xy plane SP12 and the third weight port WP3 is equal to or less than 3 mm; and

(d3) a distance between the specific xy plane SP12 and the fourth weight port WP4 is equal to or less than 3 mm.

In the present application, the height of the center of gravity of the head is defined as Gy. The height Gy can be specified by the y coordinate of the center of gravity of the head. In the present application, the position of the center of gravity of the head in the toe-heel direction is defined as Gx. The position Gx can be specified by the x-coordinate of the center of gravity of the head.

The head 2 is configured to change the position Gx without changing the height Gy. The position Gx can be changed without (substantially) changing the height Gy by changing the mass distribution of the weights disposed in the four weight ports. Therefore, the freedom degree of the adjustment is improved. For example, each golfer can easily adjust the sweet spot according to the position of the golfer's hitting point. The phrase “without changing the height Gy” means that the change of the height Gy is equal to or less than 1.0 mm.

The head 2 is configured to change the height Gy without changing the position Gx. The height Gy can be changed without (substantially) changing the position Gx by changing the mass distribution of the weights disposed in the four weight ports. Therefore, the freedom degree of the adjustment is improved. For example, each golfer can easily adjust the sweet spot according to the position of the golfer's hitting point. The phrase “without changing the position Gx” means that the change of the position Gx is equal to or less than 1.0 mm.

In the present application, the principal axis of inertia of the head is considered. All objects have been known to have three principal axes of inertia orthogonal to each other. The head 2 also has three principal axes of inertia orthogonal to each other. Due to the mass and position of the weight, the mass distribution of the head 2 is changed, and the direction of the principal axis of inertia is also changed.

Of three principal axes of inertia orthogonal to each other, a principal axis of inertia having the smallest angle with respect to the y-axis is projected on the xy plane to obtain a straight line. The straight line is defined as a base line, and the angle between the base line and the y-axis is defined as an inclination of the principal axis of inertia. The angle is an angle in the planar view.

In the head 2, the inclination of the principal axis of inertia can be changed without (substantially) changing the height Gy and the position Gx. Therefore, the freedom degree of the adjustment is improved. For example, each golfer can easily adjust the inclination of the principal axis of inertia according to the distribution of the golfer's hitting points. The phrase “without changing the height Gy and the position Gx” means that the change of the height Gy is equal to or less than 1.0 mm, and the change of the position Gx is equal to or less than 1.0 mm.

Preferably, under a condition where the mass of the head is constant, the adjustable range of the height Gy is 1 mm or greater and 10 mm or less. The adjustable range of 1 mm or greater improves an effect by the height Gy. Since the weight is heavy when the adjustable range is greater than 10 mm, the mass of the head may be excessive. From the viewpoint of obtaining such a preferable adjustable range, a plurality of weights are preferably used. From the viewpoint of the freedom degree of the adjustment, the plurality of weights may include weights having masses different from each other.

Preferably, under a condition where the mass of the head is constant, the adjustable range of the position Gx are 1 mm or greater and 15 mm or less. The adjustable range of 1 mm or greater improves an effect by the position Gx. Since the weight is heavy when the adjustable range is greater than 15 mm, the mass of the head may be excessive. From the viewpoint of obtaining such a preferable adjustable range, a plurality of weights are preferably used. From the viewpoint of the freedom degree of the adjustment, the plurality of weights preferably include weights having masses different from each other.

Preferably, under a condition where the mass of the head is constant, the adjustable range of the inclination of the principal axis of inertia is 1 degree or greater and 20 degrees or less. The adjustable range of 1 mm or greater improves an effect due to the inclination of the principal axis of inertia. Since the weight is heavy when the adjustable range is greater than 20 degrees, the mass of the head may be excessive. From the viewpoint of obtaining such a preferable adjustable range, a plurality of weights are preferably used. From the viewpoint of the freedom degree of the adjustment, the plurality of weights preferably include weights having masses different from each other.

[Weight]

The head 2 includes at least one weight. The number of the weights may be 1. When one weight is moved to a plurality of positions, the mass distribution in the head 2 is largely changed. When one weight is moved to a plurality of positions, the center of gravity of the head can be largely moved.

A preferable weight is detachably attached to the first weight port WP1, and is detachably attached to the second weight port WP2. A preferable weight is detachably attached to the third weight port WP3, and is detachably attached to the fourth weight port WP4. A more preferable weight is detachably attached to all of the first weight port WP1, the second weight port WP2, the third weight port WP3, and the fourth weight port WP4.

The head 2 may have a plurality of weights. The number of the weights may be 2, 3, 4, 5 or greater. The plurality of weights may have masses different from each other. It is preferable that each of the plurality of weights can be detachably attached to all of the first weight port WP1, the second weight port WP2, the third weight port WP3, and the fourth weight port WP4.

FIG. 5 is a perspective view of the head 2 viewed from a sole side. A weight attaching/detaching mechanism M1 is provided in the third weight port WP3. The weight attaching/detaching mechanism M1 satisfies the Golf Rules defined by Royal and Ancient Golf Club of Saint Andrews (R&A). That is, the weight attaching/detaching mechanism satisfies requirements specified in “1b Adjustability” in “1 Club” of “Appendix II Design of Clubs” defined by R&A. The requirements defined by the “1b Adjustability” are the following items (i), (ii), and (iii):

(i) the adjustment cannot be readily made;

(ii) all adjustable parts are firmly fixed and there is no reasonable likelihood of them working loose during a round; and

(iii) all configurations of adjustment conform with the Rules.

The above-mentioned weight attaching/detaching mechanism M1 is provided also in the fourth weight port WP4.

FIG. 5 includes an exploded perspective view of the weight attaching/detaching mechanism M1. One of the two weight attaching/detaching mechanisms M1 is shown in the exploded perspective view. As shown in the exploded perspective view, the weight attaching/detaching mechanism M1 includes a socket 20 and a weight 22. The first weight attaching/detaching mechanism M1 is fixed to the third weight port WP3. A recess is formed in the third weight port WP3. The first socket 20 is accommodated in the recess. The second weight attaching/detaching mechanism M1 is fixed to the fourth weight port WP4. A recess is formed in the fourth weight port WP4. The second socket 20 is accommodated in the recess.

The socket 20 includes a body part 20a and a bottom forming part 20b. The body part 20a has a hole 24. The hole 24 passes through the body part 20a. The socket 20 is fixed to the recess with an adhesive.

When the weight 22 is inserted into the hole 24, and the weight 22 is rotated at a predetermined angle θ, the weight 22 is fixed to the socket 20. Even when the weight 22 is subjected to the shock of the hit ball, the fixation of the weight 22 is maintained. When the weight 22 is inversely rotated at an angle θ, the weight 22 is detached from the socket 20. The weight 22 can be rotated by a torque wrench. The socket 20 is configured so that the weight 22 can be attached and detached as described above.

The weight attaching/detaching mechanism M1 is an attachment type attaching/detaching mechanism. As described above, in the weight attaching/detaching mechanism M1, the weight can be attached by the rotation of the angle θ, and the weight can be detached by the inverse rotate of the angle θ. In the weight attaching/detaching mechanism M1, the weight is easily attached and detached. Such a weight attaching/detaching mechanism M1 is known. The weight attaching/detaching mechanism M1 is adopted for “SRIXON Z925 driver” (trade name) manufactured by Dunlop Sports Co., Ltd. or the like.

Thus, the weight 22 can be detachably attached to the socket 20. Therefore, the weight 22 is detachably attached to the third weight port WP3. Similarly, the weight 22 is detachably attached to the fourth weight port WP4.

Although not shown in the drawings, the weight attaching/detaching mechanism M1 may be applied also to each of the first weight port WP1 and the second weight port WP2.

The weight attaching/detaching mechanism is not limited to the above-mentioned mechanism M1. Another examples of the weight attaching/detaching mechanism include a screw type mechanism.

FIG. 6 is a top view of a head 30 according to a second embodiment, and FIG. 7 is a bottom view of the head 30. Except for the disposals of a first weight port WP1, second weight port WP2, third weight port WP3, and fourth weight port WP4, the head 30 is the same as the above-mentioned head 2. In FIGS. 6 and 7, each of the weight ports is simplistically represented by hatching.

The first weight port WP1 is provided on a face side with respect to the center of gravity HG. The second weight port WP2 is provided on a face side with respect to the center of gravity HG. The third weight port WP3 is provided on a face side with respect to the center of gravity HG. The fourth weight port WP4 is provided on a face side with respect to the center of gravity HG. The positions of these weight ports contribute to bring a center of gravity of the head near the face. The center of gravity of the head near the face is useful to lower a sweet spot.

FIG. 8 is a top view of a head 40 according to a third embodiment, and FIG. 9 is a bottom view of the head 40. FIG. 10 is a side view of the head 40 viewed from a toe side. Except for the disposals of a first weight port WP1, second weight port WP2, third weight port WP3, and fourth weight port WP4, the head 40 is the same as the above-mentioned head 2. In FIGS. 9 and 10, each of the weight ports is simplistically represented by hatching.

As shown in FIG. 9, the first weight port WP1 is provided in a side part 14. The first weight port WP1 is provided in the upper part of the side part 14 . Similarly, the second weight port WP2 is provided in the side part 14. As shown in FIGS. 9 and 10, the second weight port WP2 is provided in the upper part of the side part 14. The third weight port WP3 and the fourth weight port WP4 are provided in a sole 6.

Thus, in the head 40, an upper-side weight-disposal part

Wa is provided in the side part. A lower-side weight-disposal part Wb is provided in a sole part. As shown in FIG. 8, in the head 40, the weight port is not visually recognized at address. In the head 40, the upper-side weight-disposal part is not visually recognized at address.

FIG. 11 is a top view of a head 50 according to a fourth embodiment, and FIG. 12 is a bottom view of the head 50. In FIG. 11, each of the weight ports is simplistically represented by hatching.

In the head 50, a first weight port WP1 and a second weight port WP2 are provided in a crown 4. An upper-side weight-disposal part Wa is constituted of the first weight port WP1 and the second weight port WP2 as in the above-mentioned head 2. Meanwhile, in the head 50, a lower-side weight-disposal part Wb is a weight slide mechanism. As shown in FIG. 12, the weight slide mechanism has a weight wl, a slide groove v1, and a screw t1. A slit s1 is formed in a bottom face of the slide groove v1. The slide groove v1 extends substantially along a toe-heel direction. The screw t1 passes through the weight w1 and the slit s1, and is screw-connected to a nut member (not shown). The nut member is disposed inside a head body h1, and has such a size that the nut member does not pass through the slit s1.

The weight w1 can be slid in the slide groove v1. By tightening the screw tl, the weight w1 can be fixed at an optional position in the slide groove v1. By the movement of the weight w1, mass distribution in the toe-heel direction can be changed. Thus, the lower-side weight-disposal part Wb may be a weight slide mechanism. Similarly, the upper-side weight-disposal part Wa may be a weight slide mechanism. The upper-side weight-disposal part Wa may be a weight slide mechanism, and the weight slide mechanism may be provided in a side part 14.

FIG. 13 is a top view of a head 60 according to a fifth embodiment, and FIG. 14 is a bottom view of the head 60. In FIG. 13, a weight port is simplistically represented by hatching.

In the head 60, a first weight port WP1 is provided in a crown 4. Unlike the above-mentioned head 50, a second weight port WP2 is not provided in the head 60. The same weight slide mechanism as the weight slide mechanism of the head 50 is provided in a sole 6 of the head 60.

In the head 60, an upper-side weight-disposal part Wa is constituted of only the first weight port WP1. The upper-side weight-disposal part Wa is not configured to change mass distribution in a toe-heel direction. Meanwhile, a lower-side weight-disposal part Wb is the above-mentioned weight slide mechanism. The lower-side weight-disposal part Wb is configured to change mass distribution in the toe-heel direction.

FIG. 15 is a top view of a head 70 according to a sixth embodiment, and FIG. 16 is a bottom view of the head 70. Except for the disposals of a first weight port WP1, second weight port WP2, third weight port WP3, and fourth weight port WP4, the head 70 is the same as the above-mentioned head 2. In FIGS. 15 and 16, each of the weight ports is simplistically represented by hatching.

As shown in FIG. 15, the first weight port WP1 is provided on a face side with respect to a center of gravity HG of a head body h1. Similarly, the second weight port WP2 is provided on a face side with respect to the center of gravity HG. Meanwhile, as shown in FIG. 16, the third weight port WP3 is provided on a back side with respect to the center of gravity HG. Similarly, the fourth weight port WP4 is provided on a back side with respect to the center of gravity HG. The positions of these weight ports contribute to the adjustment of the position of the center of gravity of the head in a face-back direction.

The specific xy plane SP1 exists also in the head 70. As described above, the specific xy plane SP1 satisfies all of the following (a) to (d) .

(a) a distance between the specific xy plane SP1 and the first weight port WP1 is equal to or less than 20 mm;

(b) a distance between the specific xy plane SP1 and the second weight port WP2 is equal to or less than 20 mm;

(c) a distance between the specific xy plane SP1 and the third weight port WP3 is equal to or less than 20 mm; and

(d) a distance between the specific xy plane SP1 and the fourth weight port WP4 is equal to or less than 20 mm.

The material of the head body h1 is not limited. Examples of the material of the head body h1 include a metal and CFRP (carbon fiber reinforced plastic). Examples of the metal include one or more kinds selected from soft iron, pure titanium, a titanium alloy, stainless steel, maraging steel, an aluminium alloy, a magnesium alloy, and a tungsten-nickel alloy. Examples of the stainless steel include SUS630 and SUS304. Examples of the titanium alloy include 6-4 titanium (Ti-6Al-4V) , Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S. The soft iron means low carbon steel having a carbon content of less than 0.3 wt %.

The material of the weight is not limited. Examples of the material of the weight include a metal. Examples of the metal include one or more kinds selected from soft iron, pure titanium, a titanium alloy, stainless steel, maraging steel, an aluminium alloy, a magnesium alloy, a tungsten-nickel alloy, and tungsten. Examples of the stainless steel include SUS630 and SUS304. Examples of the titanium alloy include 6-4 titanium (Ti-6Al -4V), Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S.

A preferable example of the head is a driver head. The driver means a number 1 wood (W#1). High flight distance performance is required for the driver. Therefore, the present invention is preferably applied. Usually, the driver head has the following constitution:

(1a) curved face surface;

(1b) hollow part;

(1c) volume of 300 cc or greater and 460 cc or less; and

(1d) real loft of 7 degrees or greater and 14 degrees or less.

Another preferable example of the head is a fairway wood head. Examples of the fairway wood include a number 3 wood (W#3) , a number 4 wood (W#4), a number 5 wood (W#5), a number 7 wood (W#7), a number 9 wood (W#9), a number 11 wood (W#11), and a number 13 wood (W#13). Usually, the fairway wood head has the following constitution:

(2a) curved face surface;

(2b) hollow part;

(2c) volume of 100 cc or greater and less than 300 cc; and

(2d) real loft of greater than 14 degrees and 33 degrees or less.

More preferably, the volume of the fairway wood head is 100 cc or greater and 200 cc or less.

Still another preferable example of the head is a utility type head (hybrid type head). Usually, the utility type head (hybrid type head) has the following constitution:

(3a) curved face surface;

(3b) hollow part;

(3c) volume of 100 cc or greater and 200 cc or less; and

(3d) real loft of 15 degrees or greater and 33 degrees or less.

More preferably, the volume of the utility type head (hybrid type head) is 100 cc or greater and 150 cc or less.

The present invention can be preferably used also for an iron head and a putter head.

EXAMPLES

Hereinafter, the effects of the present invention will be clarified by Examples. However, the present invention should not be interpreted in a limited way based on the description of Examples.

[Production of Head Body]

Three-dimensional data having the same shape as the shape of the above-mentioned head body hl was produced. The shape of the head body h1 was made the same as the shape of “SRIXON Z925 driver (trade name): loft 9.5 degrees” manufactured by Dunlop Sports Co., Ltd. Four weight ports WP1, WP2, WP3, and WP4 were set as in the above-mentioned head 2. The positions of the third weight port WP3 and fourth weight port WP4 were made the same as the positions of weight ports provided in “SRIXON Z925 driver”.

The following Table 1 shows the position of the center of gravity of the weight disposed in each weight port. Disposal A represents the coordinate of the center of gravity of a weight of 8 g when the weight is disposed in only the second weight port WP2. Disposal B represents the coordinate of the center of gravity of a weight of 8 g when the weight is disposed in only the first weight port WP1. Disposal C represents the coordinate of the center of gravity of a weight of 8 g when the weight is disposed in only the third weight port WP3. Disposal D represents the coordinate of the center of gravity of a weight of 8 g when the weight is disposed in only the fourth weight port WP4.

As represented by these coordinates, the first weight port WP1 is in the first quadrant Q1 in planar view; the second weight port WP2 is in the second quadrant Q2 in planar view; the third weight port WP3 is in the third quadrant Q3 in planar view; and the fourth weight port WP4 is in the fourth quadrant Q4 in planar view. The coordinates shown in Table 1 are values when the position of the center of gravity of reference example is defined as an origin. The reference example is a head to which a weight is not attached. The center of gravity of the reference example is a center of gravity HG of the head body h1.

For example, when a specific xy plane SP1 was set at a position of which a z coordinate was 29.0, all the distances between the specific xy plane SP1 and each of the coordinates were less than 10 mm (furthermore, less than 3 mm).

Example 1

The head body was equipped with four weights. The masses of these weights were 4 g. Weights were disposed in all of the four weight ports. The position of the center of gravity of the head of Example 1 was calculated. Furthermore, the inclination of a principal axis of inertia was calculated. The results are shown in the following Table 2. The sign of the inclination of the principal axis of inertia is equal to the sign of the inclination of the base line with respect to the y-axis in an xy coordinate system, and clockwise rotation is positive.

Example 2

Two weights were used in Example 2. The masses of these weights were 8 g. The weights were disposed in a second weight port WP2 and a third weight port WP3. In the same manner as in Example 1 as for the rest, the position of a center of gravity and the inclination of a principal axis of inertia of a head of Example 2 were obtained. As the position of the center of gravity of the head, the relative position of the center of gravity of Example 2 with respect to the reference example having no weight and the relative position of the center of gravity of Example 2 with respect to Example 1 were calculated. These results are shown in the following Table 2.

Examples 3 to 7

Two weights were used also in Examples 3 to 7. The positions of the centers of gravity (two kinds) and the inclinations of principal axes of inertia of heads of Examples 3 to 7 were calculated in the same manner as in Example 2 except that the disposals of the weights were as shown in Table 2. These results are shown in the following Table 2.

TABLE 1
Position of weight disposed in each weight port
			Reference
		Weight	example	Disposal	Disposal	Disposal	Disposal
		port	(head body)	A	B	C	D
Disposal of	Toe side of	WP2	0	8	0	0	0
single	crown
weight (g)	Heel side	WP1	0	0	8	0	0
	of crown
	Toe side of	WP3	0	0	0	8	0
	sole
	Heel side	WP4	0	0	0	0	8
	of sole
Relative	x (mm)	—	0.0	−31.3	20.6	−35.2	24.8
position of	y (mm)	—	0.0	26.8	18.6	−4.8	−8.6
center of	z (mm)	—	0.0	29.7	26.0	31.3	27.9
gravity of
weight (with
respect to
no weight)

TABLE 2
Specifications and evaluation results of Examples
		Weight	Example	Example	Example	Example	Example	Example	Example
		port	1	2	3	4	5	6	7
Disposal of	Toe side of	WP2	4	8	0	8	0	8	0
weight (g)	crown
	Heel side	WP1	4	0	8	8	0	0	8
	of crown
	Toe side of	WP3	4	8	0	0	8	0	8
	sole
	Heel side	WP4	4	0	8	0	8	8	0
	of sole
Relative	x (mm)	—	−0.4	−2.7	1.8	−0.4	−0.4	−0.3	−0.6
position of	y (mm)	—	0.7	0.9	0.4	1.8	−0.5	0.7	0.6
center of	z (mm)	—	2.3	2.5	2.2	2.3	2.4	2.3	2.3
gravity
(with
respect to
no weight)
Relative	x (mm)	—	0.0	−2.3	2.3	0.0	0.0	0.2	−0.2
position of	y (mm)	—	0.0	0.2	−0.2	1.2	−1.2	0.1	−0.1
center of	z (mm)	—	0.0	0.1	−0.1	−0.1	0.1	0.0	0.0
gravity
(with
respect to
Example 1)
Inclination of principal	—	−2.4	−0.9	−4.1	−3.1	−1.9	0.7	−5.3
axis of inertia (degree)

Examples 1 to 7 had the same head mass. In Examples 2 to 7, two weights were used, and the freedom degree of the position of the center of gravity was high. In comparison of Example 2 with Example 3, an x-coordinate was changed by 4 mm or greater while the changes of y and z coordinates were suppressed to 0.4 mm or less. That is, the amount of change of the x-coordinate was equal to or greater than 10 times based on the amounts of change of the y and z coordinates. In comparison of Example 4 with Example 5, a y-coordinate was changed by 2 mm or greater while the changes of x and z coordinates were suppressed to 0.1 mm or less. That is, the amount of change of the y-coordinate was equal to or greater than 20 times based on the amounts of change of the x and z coordinates. In comparison of Example 6 with Example 7, the inclination of a principal axis of inertia was changed by 5 mm or greater while the changes of x, y and z coordinates were suppressed to 0.2 mm or less. Thus, the adjustment of the center of gravity of the head was achieved with a high freedom degree. The freedom degree allows adjustment complying with each golfer. The freedom degree facilitates custom fitting.

The present invention can be applied to all golf club heads such as a wood type, utility type, hybrid type, iron type, and putter type golf club heads.

The above description is only illustrative and various changes can be made without departing from the scope of the present invention.

Claims

1. A golf club head comprising:

a head body; and

at least one weight, wherein:

the head body includes an upper-side weight-disposal part positioned on an upper side of a center of gravity of the head body, and a lower-side weight-disposal part positioned on a lower side of the center of gravity of the head body; and

at least one of the upper-side weight-disposal part and the lower-side weight-disposal part is configured to change mass distribution in a toe-heel direction.

2. The golf club head according to claim 1, wherein:

the upper-side weight-disposal part is constituted of a first weight port and a second weight port; and

the lower-side weight-disposal part is constituted of a third weight port and a fourth weight port.

3. The golf club head according to claim 2, wherein if the center of gravity of the head body is defined as an origin in a base state where the head is disposed on a level surface at a predetermined lie angle and loft angle; a straight line in the toe-heel direction passing through the origin is defined as an x-axis; a straight line in a vertical direction passing through the origin is defined as a y-axis; and a plane parallel to the x-axis and the y-axis is defined as an xy plane, a specific xy plane satisfying all of the following (a) to (d) exists:

(a) a distance between the specific xy plane and the first weight port is equal to or less than 20 mm;

(b) a distance between the specific xy plane and the second weight port is equal to or less than 20 mm;

(c) a distance between the specific xy plane and the third weight port is equal to or less than 20 mm; and

(d) a distance between the specific xy plane and the fourth weight port is equal to or less than 20 mm.

4. The golf club head according to claim 3, wherein:

an xy coordinate system is constituted of the x-axis and the y-axis in planar view from a face side; and

in the planar view, the first weight port is positioned in a first quadrant of the xy coordinate system; the second weight port is positioned in a second quadrant of the xy coordinate system; the third weight port is positioned in a third quadrant of the xy coordinate system; and the fourth weight port is positioned in a fourth quadrant of the xy coordinate system.

5. The golf club head according to claim 3, wherein:

the golf club head includes three principal axes of inertia orthogonal to each other; and

of the three principal axes of inertia, a principal axis of inertia having the smallest angle with respect to the y-axis is projected on the xy plane to obtain a straight line, the straight line is defined as a base line, and the angle between the base line and the y-axis is defined as an inclination of the principal axis of inertia; a height of a center of gravity of the head is defined as Gy; and a position of the center of gravity of the head in the toe-heel direction is defined as Gx,

the head is configured to change the inclination of the principal axis of inertia without changing the height Gy and the position Gx.

6. The golf club head according to claim 1, wherein if a height of a center of gravity of the head is defined as Gy and a position of the center of gravity of the head in the toe-heel direction is defined as Gx, the head is configured to change the position Gx without changing the height Gy, and the head is configured to change the position Gy without changing the position Gx.

7. The golf club head according to claim 5, wherein an adjustable range of the height Gy is 1 mm or greater and 10 mm or less under a condition where amass of the head is constant.

8. The golf club head according to claim 5, wherein an adjustable range of the position Gx is 1 mm or greater and 15 mm or less under a condition where a mass of the head is constant.

9. The golf club head according to claim 1, wherein:

the golf club head includes three principal axes of inertia orthogonal to each other; and

of the three principal axes of inertia, a principal axis of inertia having the smallest angle with respect to the y-axis is projected on the xy plane to obtain a straight line, the straight line is defined as a base line, and the angle between the base line and the y-axis is defined as an inclination of the principal axis of inertia,

an adjustable range of the inclination of the principal axis of inertia is 1 degree or greater and 20 degrees or less under a condition where a mass of the head is constant.