Adjustable stiffness shaft structure

Abstract

A shaft structure with an adjustable stiffness is provided for golf clubs, fishing rods and like apparatuses. The shaft structure employs an inner and outer shaft structure. The golfer, in practice, configures the stiffness of a golf shaft, by adjusting the pressure of an inner shaft structure. The combination of outer and inner shaft structure stiffness results in an advantageous stiffness profile. The golfer can, at any time and very easily, change the stiffness profile of the golf shaft.

Description

FIELD OF THE INVENTION[0001]This invention relates to shafts for golf clubs, fishing rods and like apparatuses and more particularly where the stiffness of these devices can be adjusted by the user in an advantageous manner to match their physical abilities.BACKGROUND OF THE INVENTION[0002]Golf shafts are typically manufactured with a predetermined stiffness or flex. The stiffness of a golf shaft refers to its resistance to bend under load and is typically measured as the amount of deflection the shaft experiences when the shaft is positioned horizontally and subjected to a constant force. Presently, golf shafts are mass produced with a predefined stiffness or flex without regard for a golfer's individual swing mechanics. Typically, the flex is provide in discreet stiffness's such as A, R, S, X. These flex ranges are designed in an attempt to accommodate a vast multitude of golfers.[0003]The correct stiffness of a golf shaft plays a pivotal role in proper club performance. A golf sh...

AI Technical Summary

Benefits of technology

[0009]In order for a golf club to be effective and ultimately configured for a golfer by the golfer without requiring the golfer to have intimate knowledge or club-building skills, the present invention provides for a device that can be easily changed to accommodate the golfer's abilities for any given day any given weather condition and course conditions as well. The invention allows the golfer the unique ability to tune a golf club from observations of ball flight while they are using the golf club rather than having to seek out a club-maker and use misleading equipment which is time consuming and costly.

[0010]The present invention overcomes the inability of prior art shafts in providing the ability to change the stiffness of a golf shaft. A shaft structure is provided which can be easily and safely tuned, to match the golfer's abilities so as to maximize both shot accuracy and distance while maintaining an acceptable weight.

[0011]More particularly, this invention relates to a shaft structure for golf clubs, fishing poles and like apparatuses incorporating an innovative variable stiffness shaft-in-a-shaft structure without compromising other performance characteristics such as weight or structurally integrity and safety as well. Additionally, the present invention does not serve to change the stiffness of shaft structure by imposing an axial stress or compression force upon the shaft but rather provides for a device which allows for the changing of the stiffness of shaft structure by virtue of a shaft-in-a-shaft structure wherein the absolute overall stiffness is born from the compounded stiffness of both the inner and outer shaft structure stiffness acting in a total harmonious arrangement. As such, existing golf shafts can be easily retrofitted with the present invention.

Problems solved by technology

A golf shaft that is too flexible tends to promote a hook whereas a golf shaft that is too stiff tends to cause the golf ball to slice.

Typically, the process is time consuming and involves numerous pieces of equipment, expertise and expense.

However, a golfer's performance can dramatically change over time.

The heavier, liquid filled golf shaft will profoundly slow down a golfer's swing speed thereby resulting in an unacceptable loss of distance which would, of course, have a, detrimental effect.

Golf shafts that are filled with a compressible gas such helium cannot possibly provide a force great, enough to affect a stiffness change without requiring extremely high pressures due to the high Young's modulus of the material used in modern golf shafts such as graphite composites.

These high pressures are most assuredly unachievable and absolutely unacceptable from a safety standpoint.

The anticipated high pressures would create a potentially serious situation if the golf shaft were to rupture such as would be the case when all irate golfer would strike the ground with their club or strike a tree.

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