Golf club

Description

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a golf club that increases the distance of a struck ball and stabilizes the direction of a struck ball.

2. Description of the Related Art

Golf clubs designed to increase the head speed and the flight distance of the golf ball by, for instance, making the head (or clubhead) lighter have been widely known as, for example, disclosed in Japanese Patent Application Laid-Open (Kokai) Nos. 2004-531 and 2003-135629.

Generally, the striking force F at the moment of impact with such golf clubs is expressed as ½×m×v² (where m is the mass of the head, and v is the head speed). The striking force F is proportional to the mass m of the clubhead and is also proportional to the square of the head speed v. To increase the flight distance, this striking force F must be increased.

Nevertheless, in conventional golf clubs, though the head speed v can indeed be increased a certain amount by lightening the clubhead, since a reduction in the mass m of the head results in a reduction in the striking force F, there is a specific limit to how much a head can be lightened, and this approach also makes it difficult to increase the flight distance.

Also, giving the shaft a suitable amount of flexibility and taking advantage of the bending of the shaft are common ways to increase the flight distance. However, if the shaft is too flexible, the directionality of the struck ball will suffer, and poor directionality becomes a particular problem when the lie angle of the clubhead is off at the point of impact.

BRIEF SUMMARY OF THE INVENTION

The present invention is to solve the above-described problems, and it is an object of the present invention to provide a golf club that increases the directional stability and flight distance of a struck ball.

The above object is accomplished by a unique structure of the present invention for a golf club that includes:

• • a head which has a mass of at least 160 g and no more than 180 g and through which is formed a tapered hosel hole whose diameter increases from the upper portion of the head to the bottom portion of the head, and
  • a shaft that has a hardness of characteristic frequency of 225 cpm or less; and in the present invention:
  • the head is equipped with a shaft attachment member that is inserted and fixed in the hosel hole from the bottom side of the head and that has an external shape which is substantially the same as the shape of the hosel hole, and within the shaft attachment member is formed a shaft insertion hole that is inclined at a specific angle with respect to the sole surface of the head and into which the shaft is inserted from the upper side of the head, and
  • the shaft is equipped therein with a shaft vibration damping member comprising a substantially cylindrical fixture component, which is tightly fixed to the shaft and is disposed coaxially with the shaft, and a vibration component, which is provided in the fixture component and vibrates independently from the shaft.

In this structure, the shaft can be hollow, and the shaft vibration damping member can be disposed within the hollow space inside the shaft.

Furthermore, the shaft attachment member can be made of a plurality of segmented members that are segmented in the peripheral direction, and the shaft insertion hole in the shaft attachment member may have a closed bottom.

In addition, the space between the hosel hole of the head and the outer peripheral surface of the shaft attachment member, and the space between the shaft and the inner peripheral surface of the shaft insertion hole of the shaft attachment member can be filled with an adhesive for fixing the shaft attachment member to the head and shaft.

The above object is further accomplished by another unique structure of the present invention for a golf club that includes:

• • a head which has a mass of at least 160 g and no more than 180 g and through which is formed a tapered hosel hole whose diameter increases from the upper portion of the head to the bottom portion of the head, and
  • a shaft that has a hardness of characteristic frequency of 225 cpm or less; and in the present invention:
  • the head is equipped with a substantially plate-form shaft supporting member that is inserted and fixed in the hosel hole from the bottom side of the head, and within the shaft supporting member is formed a shaft insertion hole in which the shaft is inserted, and
  • the shaft is equipped with a shaft vibration damping member comprising a substantially cylindrical fixture component, which is tightly fixed to the shaft and is disposed coaxially with the shaft, and a vibration component, which is provided in the fixture component and vibrates independently from the shaft.

In this structure, the hosel hole in the head can be filled with an adhesive for fixing the shaft to the head.

In addition, the inside diameter of the upper opening of the hosel hole in the head can be substantially the same as the outside diameter of the shaft that is to be inserted into the hosel hole.

With the structure of the present invention described above, the golf club of the present invention provides an excellent effect that increases the directional stability and flight distance of a struck ball.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross sectional view of the golf club of Embodiment 1 according to the present invention;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is an oblique view of the shaft attachment member of used in the golf club of the present invention;

FIG. 5 shows in cross section the detail of the vicinity of the shaft vibration damping member used in the golf club of the present invention;

FIG. 6 is a cross sectional view of the golf club of Embodiment 2 according to the present invention;

FIG. 7 is a cross sectional view of the golf club of Embodiment 3 according to the present invention; and

FIG. 8 is an oblique view of the shaft supporting member used in the golf club of Embodiment 3.

DETAILED DESCRIPTION OF THE INVENTION

The golf club of the present invention will now be described in detail with respect to the accompanying drawings.

Embodiment 1

As shown in FIGS. 1 to 3, a golf club 10 of Embodiment 1 of the present invention is comprised of a head (clubhead) 12, through which a hosel hole 12A is formed, and a shaft 14 fixed to this head 12.

The head 12 has a mass of 160 g or larger and 180 g or less; and in this Embodiment, it is designed to have a low center of gravity in order to increase the flight distance. The hosel hole 12A in the head 12 has a tapered shape so that the diameter of the hosel hole 12A increases from the upper portion of the head 12 toward the bottom. The inside diameter of the upper opening of this hosel hole is the same as the outside diameter of the shaft 14 that is to be inserted into the hosel hole 12A. The head 12 is also equipped with a shaft attachment member 16 whose external shape is substantially the same as the shape of the hosel hole 12A.

As shown in FIG. 4, the shaft attachment member 16 is comprised of two segmented members, namely, a first attachment unit 16A and a second attachment unit 16B. The shaft attachment member 16 is inserted and fixed in the hosel hole 12A from the bottom side of the head 12. A shaft insertion hole 16C is formed in the shaft attachment member 16. The centerline axis L1 of shaft insertion hole 16C is inclined at a specific angle α with respect to the sole surface 12B of the head 12; and into the shaft insertion hole 16C, the shaft 14 is inserted from the upper side of the head 12. The specific angle α here refers to what is known as the lie angle. The lie angle can be suitably set according to the user of the golf club, and it is preferable to set to be an angle of approximately 52° to 61°.

The shaft 14 has hardness in which the characteristic frequency is 225 cpm or less; and in this Embodiment, the shaft has a closed bottom and is hollow inside. The hardness of the shaft of a golf club is generally called “flex,” and the flex is expressed by one of the symbols L, A, R, RS, S, SX, X, and XX, in the order of the increasing hardness of the shaft. The characteristic frequency ω at each flex level is 185 cpm for flex L, 205 cpm for flex A, 225 cpm for flex R, 235 cpm for flex RS, 245 cpm for flex S, 255 cpm for flex SX, 265 cpm for flex X, and 275 cpm for flex XX. The shaft in the present invention has a characteristic frequency of 225 cpm or less, that is, it has a flex of L, A, or R. This shaft 14 is equipped with a shaft vibration damping member 20 within its interior space.

As shown in FIG. 5, the shaft vibration damping member 20 comprises a substantially cylindrical fixture component 22 and a vibration component 24. The fixture component 22 is tightly fixed to the shaft 14 and is disposed coaxially with the shaft 14, and the vibration component 24 is provided in the fixture component 22 so that it is able to vibrate independently from the shaft 14.

When a ball is struck with a golf club with this shaft vibration damping member 20 installed, the weight of the head 12 and the bending of the shaft 14 during the takeback and downswing of the club prior to striking the ball cause the shaft 14 to vibrate, but the vibration component 24, when it is in a non-contact state with the shaft 14, vibrates according to the vibration of the shaft 14, and if it is in a non-resonant state, then the vibration component 24 acts to suppress the vibration of the shaft.

Therefore, with the vibration component 24 installed, shaking of the head 12 is suppressed when the ball is hit, and the ball is hit much more efficiently, the result of which being a longer flight distance and better directionality of the struck ball. Furthermore, the vibration of the shaft 14 after the ball is struck is quickly attenuated by the vibration of the vibration component 24, and thus the club feels better in the hand.

When the above-described shaft attachment member 16 is used to attach the shaft 14 to the head 12, the first step is to coat the inner peripheral surface of the shaft insertion hole 16C and the outer peripheral surface of the shaft attachment member 16 with an adhesive 18 (see FIG. 1), then the shaft 14 is inserted into the shaft insertion hole 16C from the upper side of the head 12 while the shaft attachment member 16 is inserted into the hosel hole 12A from the bottom side of the head 12, and then these components are fixed. As a result, the head 12 and the shaft 14 are fixed via the shaft attachment member 16.

As seen from the above, the golf club 10 of Embodiment 1 is comprised of the head 12 and the shaft 14; and the head 12 has a mass of no more than 180 g and through which is formed the tapered hosel hole 12A whose diameter increases from the upper portion of the head 12 to the bottom portion, and the shaft 14 has the hardness with the characteristic frequency of 225 cpm or less. The head 12 is equipped with the shaft attachment member 16 that can be inserted and fixed in the hosel hole 12A from the bottom side of the head 12 and that has an external shape which is substantially the same as the shape of the hosel hole 12A; and inside of this shaft attachment member 16 is formed a shaft insertion hole 16C that is inclined at a specific angle α with respect to the sole surface 12B of the head 12 so that the shaft 14 is inserted in the shaft insertion hole 16C from the upper side of the head 12. On the other hand, the shaft 14 is equipped with the shaft vibration damping member 20, and this shaft vibration damping member 20 comprises the substantially cylindrical fixture component 22 and the vibration component 24; and the cylindrical fixture component 22 is tightly fixed to the shaft 14 and is disposed in coaxial with the shaft 14, and the vibration component 24 is provided in the fixture component 22 so that it vibrates independently from the shaft 14. Therefore, the weight reduction of the head 12 is accomplished, providing an increased head speed; and with the use of a shaft 14 that is soft, the bending of the shaft 14 is effectively utilized. Accordingly, the flight distance of the golf ball will be greater than a conventional golf club.

Also, excessive vibration by the shaft 14 is suppressed with the shaft vibration damping member 20, and the lie angle is easily adjustable with the shaft attachment member 16. As a result, the directionality of a struck ball will be more stable than with a conventional golf club. Furthermore, since the shaft attachment member 16 has a tapered shape and its external shape is substantially the same as the shape of the hosel hole 12A, the head 12 is effectively prevented from coming loose from the shaft 14.

In addition, since the shaft 14 has a hollow structure and the shaft vibration damping member 20 is provided inside the interior space of the shaft 14, the shaft vibration damping member 20 does not get in the way when the golf club is being used, nor does it adversely affect the appearance of the golf club.

Further, since the shaft attachment member 16 is comprised of two segmented members (the first attachment unit 16A and the second attachment unit 16B), the shaft attachment member 16 is easily insertable and fixed in the hosel hole 12A, making it even easier to attach and adjust the angle of the shaft 14.

In addition, since the inside diameter of the upper opening of the hosel hole 12A is substantially the same as the outside diameter of the shaft 14 that is inserted in the hosel hole 12A, the angle of the shaft 14 can be easily adjusted, using the upper opening as the point of support in fixing the shaft 14 in the hosel hole 12A, and this makes it easier to attach and adjust the angle of the shaft 14.

Embodiment 2

FIG. 6 shows Embodiment 2, and as seen from FIG. 6, the golf club 30 of Embodiment 2 includes a shaft attachment member 32 that has a shaft insertion hole 32A with its bottom closed, instead of the shaft attachment member 16 in the golf club 10 of the above-described Embodiment 1.

In the golf club 30 of Embodiment 2, since the shaft insertion hole 32A of the shaft attachment member 32 has a closed bottom, the shaft 14 can be attached to the head 12 more securely than in the golf club 10 of Embodiment 1.

Embodiment 3

FIG. 7 shows Embodiment 3, and as seen from FIG. 7, the golf club 40 of Embodiment 3 of the present invention includes a substantially plate-form shaft supporting member 42 that is inserted and fixed near the bottom of the hosel hole 12A, instead of the shaft attachment member 16 of the golf club 10 of the above-described Embodiment 1. In addition, as seen from FIG. 8, the shaft insertion hole 42A in which the shaft 14 is inserted and supported is formed in the shaft supporting member 42.

When the shaft supporting member 42 is used to attach the shaft 14 to the head 12, the shaft supporting member 42 is inserted into the hosel hole 12A and fixed in a notch 12A1 formed in this hosel hole 12A as shown in FIG. 7, and the shaft 14 is inserted into the shaft insertion hole 42A of the shaft supporting member 42. The space in the hosel hole 12A is then filled with the adhesive 44 to fix the head 12 and the shaft 14.

As seen from the above, the golf club 40 of Embodiment 3 is comprised of the head 12 and the shaft 14; and the head 12 has a mass of no more than 180 g and through which is formed a tapered hosel hole 12A whose diameter increases from the upper portion of the head 12 to the bottom portion, and the shaft 14 has a hardness of the characteristic frequency with 225 cpm or less. The head 12 is equipped with a substantially plate-form shaft supporting member 42 that is inserted and fixed in the hosel hole 12A from the bottom side of the head 12; and in this shaft supporting member 42 is formed a shaft insertion hole 42A in which the shaft 14 is inserted and supported. The shaft 14 is equipped with the shaft vibration damping member 20 and the vibration component 24; and the shaft vibration damping member 20 is comprised of a substantially cylindrical fixture component 22 which is tightly fixed to the shaft 14 and is disposed in coaxial with the shaft 14, and the vibration component 24 is provided in the fixture component 22 so that it vibrates independently from the shaft 14. Therefore, just as in the golf club 10 of Embodiment 1, the golf club 40 increases the ball flight distance and stabilizes the directionality of a struck ball.

The golf club of the present invention is not limited to the shape, structure, and so forth of the golf clubs 10, 30 and 40 of Embodiments 1 to 3 described above. For example, the shaft may have a solid structure, and the shaft vibration damping member 20 may be disposed around the outer periphery of the shaft.

Also, the shaft attachment member 16 is comprised of two segmented members (the first attachment unit 16A and the second attachment unit 16B) in the above Embodiments, but the present invention is not limited to this; and for example, the first attachment unit 16A and the second attachment unit 16B can be formed integrally.

In addition, the inside diameter of the upper opening of the hosel hole 12A is substantially the same as the outside diameter of the shaft 14 to be inserted into the hosel hole 12A in the above Embodiments; however, the present invention is not limited to this, as long as the shaft 14 can be inserted into the hosel hole 12A.