Patent Application
20140073448
The present invention relates generally to a device for adjusting the length of a golf shaft. In particular, the invention concerns modifying the length of the shaft by utilizing the device at the gripping end of the club that is not visible and does not require a special grip or shaft.
One of the more important factors in golf club equipment is the club shaft. The shaft transfers the golfer's power to the club head. Golf club shafts are available in various types of materials and structures. Steel shafts are stronger, last longer, more durable and generally less expensive than graphite or carbon fiber shafts, and are usually made from carbon steel, although stainless steel is sometimes used. The steel shafts are available in stepped or rifle designs. The graphite shafts are more expensive and less durable; however, the lighter weight creates greater swing speed for more power. Also available are multi-material and titanium shafts.
When installing a shaft, the proper length must be accurately determined. The length can be as important to a golf shaft as is the flex or torque. Most measurements of the correct shaft length for the player involve a determination of a particular player's height and distance of his hands to the floor. Shaft length will impact whereon the clubface the ball will be consistently struck, and often, an incorrect shaft length is the main cause of a golfer to alter his natural swing arc in order to make optimum impact. According to most research, if ball impact is but one inch off-center this can equate to a 14% loss of carry distance, so it is vitally important that the length of the club be accurately fitted for each particular player.
If it is seen in the fitting process that a player needs to adjust his club length, such as adding or removing a half inch, inch or two inches to the length of the club, it would be highly desirable to lengthen his present club(s) rather buy and install new shafts. Typical driver shaft lengths are from 43 to 47 inches.
Prior art shafts having adjustable lengths have been used for many years for a wide variety of applications. Each of these applications has its own functional and aesthetic requirements for the shaft construction which is employed. As a consequence, a number of different mechanisms and devices have been developed to satisfy the particular application requirements. A majority of golf club shaft extension patents are directed to use mainly as putters, or to extending shafts of an existing set of clubs to accommodate growing children. While the teachings of the present invention may be adapted to these types of applications, the focus is rather to make a club adjustment that is rigid, secure, and easily fastened. Additionally, the ability to adjust the shaft length without the need for a custom grip or a custom made shaft is desirable along with the device being hidden within the shaft and grip such that it is not distracting to the player.
The present invention provides for an extension device for use on the butt-end of a golf club shaft. The device consists of three basic parts: an upper part; a lower part; and a connecting device. The bottom part is secured into the tubular opening in the top of the club shaft. A connecting device is provided within the upper part and extending from a second end of the upper part, a distal portion of the connecting device is threadably connected to the lower part. The connecting device is engageable to adjust the position of the lower part relative to the upper part.
In another embodiment, an extension device is provided for use on a butt-end of a golf club shaft. The extension device comprises a grip secured to an upper end of a golf club shaft where the top end of the grip has a threaded cavity. A plurality of grip inserts having different lengths is provided. The inserts have threaded protrusions. The grip insert having the desired length may be selected, whereby the threaded protrusion of the grip insert engages the threaded cavity of the grip such that the grip insert is secured to the grip resulting in a club that has a desired length.
The invention can be used to extend or shorten any of the golf clubs in a set, but preferably is designed for use with a driver.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.
The upper part 106 has a first portion 118 with a first cavity 120 extending from an opening 122 at a first end 124 and a second portion 126 with a second cavity 128 that extends along the length of the upper part 106 from the first cavity 120 through the second portion 126 to an opening 130 at the second end 114 of the upper part 106. The first portion 118 has an outer surface 132 that is connected to an inner surface 134 of the grip 102. Preferably the outer surface 132 of the upper part 106 is secured within a second shaft portion 136 provided within the grip 102. This second shaft portion 136 is then secured to the inner surface 134 of the grip 102. As will be appreciated, adhesive, glue or other means may be used to secure the upper part 106 to either the grip 102 or second shaft portion 136 and the second shaft portion 136 to the grip 102. The second portion 136 of the upper part 106 remains unconnected to the grip 102, and when a second shaft portion 136 is provided, the second portion 126 extends beyond the second shaft portion 136.
The lower part 108 has an upper cavity 138 extending along its length that receives the second portion 126 of the upper part 106 and a lower threaded cavity 140 that extends along the length of the lower part 108 from the upper cavity 138. The lower part 108 is provided within the upper tubular opening 110 of the golf club shaft 100. Preferably the lower part 108 is secured within the golf club shaft 100 using adhesive or glue or other suitable means. The second portion 126 of the upper part 106 is at least partially slidably inserted into the upper cavity 138 of the lower part 108.
The connecting device 112 is provided in the first cavity 120 of the first portion 118 of the upper part 106 and extends through the second cavity 128 of the second portion 126 of the upper part 106, through the upper cavity 138 of the lower part 108 and into the threaded lower cavity 140 of the lower part 108. Preferably, the connecting device 112 is a threaded screw 142 having a head 144 and a body 146, the body 146 at least partially having threads 148 to engage with threads 150 of the threaded lower cavity 140 of the lower part 108. The head 144 fits within the cavity 120 of the first portion 118 of the upper part 106 and is prevented from exiting the upper part 106 by a threaded member 152 that engages threads 154 on sidewalls 156 of the cavity 120 to prevent movement of the screw 142 out of the upper part 106. A wave washer, nylon or delrin spacer 158 may be provided between the threaded member 152 and the head 144 of the screw 142. The threaded member 152 has an opening 160, such that a tool (not shown) may be engaged with the head 144 of the screw 142 for turning the screw 142 to engage it with the threads 150 in the threaded lower cavity 140 of the lower part 108.
As illustrated in
Referring now to
It will be appreciated that the upper end 106 of the grip 102 may have an opening 172, such that a tool, such as a screw driver, may be used to engage with the screw head 146 to turn the screw 142 in the desired direction to either move the lower part 108, and thus the shaft 100, further under or out of a lower end 174 of the grip 102. This allows the length of the shaft 100 to be adjusted without having to modify the grip 102. This allows for easy adjustment of shaft 100 length without having to change the grip 102 or use a specialized grip to adjust for a change of length. As shown in
It will be appreciated that any means of attachment may be used to secure the grip inserts 210, 212 and 214 to the upper end 206 of the grip 202. In a preferred embodiment, the cavity 204 in the grip 202 features threaded sidewalls 218 and the grip inserts 210, 212 and 214 have extensions 220 with reciprocating threads 222 that engage with the sidewall threads 218 to removably secure the grip insert 210, 212 and 214 to the grip 202. Alternatively, the grip inserts 210, 212 and 214 and grip cavity 204 may feature a snap-fit feature or other mechanism to secure the grip inserts 210, 212 and 214 to the grip 202. It will be appreciated that a change in swing weight with the different grip inserts 210, 212 and 214 may be accounted for by having the grip inserts 210, 212 and 214 be different weights by using different materials of different densities or by the construction of the grip inserts 210, 212 and 214 by making them hollow or filled. Additionally, the grip inserts 210, 212 and 214 may accommodate different weight mechanisms so that the grip inserts 210, 212 and 214 may additionally add or remove weight from the grip 202. Generally the mass of the inserts may alter the weight of the grip by 1 to 60 grams, preferably between 5 and 40 grams. Additionally or alternatively, the club head itself may be designed such that it has adjustable weights.
Unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting form the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
