WEIGHT SECURED BY EXPANSION ELEMENT IN GOLF CLUB SHAFT
A golf club counter-weighting system, viable for both original manufacture and after-marketing, features an expandable weight assembly that is easily installed at a designated location within a golf club shaft and expanded via a user tool so as to become reliably secured in place by frictional pressure against the surrounding shaft. In a primary embodiment, the weight assembly is made to be threadedly engagable by the opposite end of a dual-function user tool enabling the weight assembly, when unexpanded, to be conveniently moved axially for initial installation, relocation and/or removal.
The present invention relates to the field of sports equipment, and more particularly to golf club counter-weighting for improving a golfer's playing and score by more optimally matching the golf club to the dynamic physical characteristics of the individual golfer, by adding a weighting assembly secured at a designated location in a hollow shaft of golf club.
BACKGROUND OF THE INVENTIONThere has been an evolution in golf club technology that has led to ultra light-weight thin-wall hollow shafts. These have intensified concern about optimally matching the amount of mass, including its location and distribution in the golf club, to the physical characteristics of the individual golfer, considering swing dynamics.
Along with attention that has been given to optimizing the mass at the club head end for the lightweight shaft, there has been recognition that better control, distance and accuracy can be obtained by counterbalancing the mass of the club head by the addition of mass at a selected desirable location along the shaft, where a judicial amount of mass can be selected to optimally match the player's physiological characteristics.
Typically, a weight element assembly, a.k.a. “counterweight” and “swing-weight” for adding inside the shaft of a previously manufactured golf club, requires special mounting arrangements to provide rugged lateral retention to prevent vibration and metal-to-metal contact, and rugged axial retention to prevent displacement of the added weight element assembly relative to the shaft due to slippage under the rigors and stresses of actual golf play.
DISCUSSION OF KNOWN ARTIn the practice of known art, implementations for providing the required axial retention fall into three main categories:
Category 1: securing the weight assembly to the golf club grip, requiring a custom-designed grip or modification of the cap region of a previously manufactured grip for access to enable insertion, locking in place, adjustment and removal of added weight elements, requiring at least enlargement of any original vent hole;
Category 2: securing the weight assembly using friction applied against the interior surface of the golf club shaft, either by (a) one or more expansion elements attached to (or constituting) weight elements, typically requiring special tools for installation, location adjustment and removal, (b) specialized resilient sleeves on weight elements, or (c) a specialized resilient lining on the shaft interior surface; however subcategories (b) and (c) present challenging difficulties due to the conflicting requirements of providing both the compressive holding force for reliable frictional axial retention while also enabling convenient axial adjustment and trouble-free removal or readjustment if required, and furthermore accommodating the diameter variations in tapered shafts.
Category 3: deriving the required axial retention from the top end surface of the golf club shaft, e.g. by an annular flange, configured at the top end of the weight assembly, held under the cap region of an original unmodified grip, thus avoiding grip modification and avoiding dependency on friction-gripping the interior surface of the shaft. The annular flange, dimensioned to fit closely inside the grip, co-operates therewith to also provide radial retention of an upper portion of the weight assembly.
U.S. Pat. No. 7,481,716 for GOLF GRIP FOR ACCOMODATING SELECTABLE WEIGHT ASSEMBLY by J. Johnson, the present inventor, discloses an example of category 1, implemented with the grip cap modified by a stepped circular opening, in conjunction with category 2(a).
U.S. Pat. No. 8,177,658 for WEIGHT DEVICE ADJUSTABLY SECURED IN GOLF CLUB SHAFT by J. Johnson, the present inventor, discloses an example of category (1) implemented with the grip cap modified by a (non-stepped) simple circular opening, in conjunction with category 2(a).
U.S. Pat. No. 8,641,551 for VERSATILE VIBRATION-DAMPED GOLF CLUB SWING WEIGHT and a division thereof, U.S. Pat. No. 9,283,453 issued Mar. 15, 2016 for VERSATILE VIBRATION-DAMPED GOLF CLUB SWING WEIGHT METHOD, by J. Johnson, the present inventor, as an example of category 2(a), discloses and shows in
U.S. Published Application 2014/0342845 A1 to Dingman (and now Johnson), published Nov. 20, 2014 for GRIP AND INTERNAL WEIGHT SYSTEM FOR SHAFT OF GOLF CLUB, exemplifies category 1, showing in
There remains an unfulfilled need for an improved golf club weighting system that (a) provides category 2 secure axial retention of the weight assembly by an expansion element in the shaft, and (b) is readily viable both in original manufacture, after-marketing and user golf play.
OBJECTS OF THE INVENTIONIt is a primary object of the present invention to provide an improved expansion/friction type weight assembly implementation that fulfills the above-described unfulfilled need, including structure that engages the weight assembly positively for upward adjustment or removal, and that can be readily and easily incorporated into golf clubs at original manufacture as well as in the aftermarket and user golf play.
SUMMARY OF THE INVENTIONThe foregoing object has been met by the disclosed golf club counter-weighting system, viable for original manufacture, after-marketing and user golf play, featuring an expandable weight assembly that is easily installed at a designated location within a golf club shaft and expanded via a user expansion tool so as to become reliably secured in place by frictional pressure against the surrounding shaft. In a primary embodiment, the weight assembly is made to be threadedly engagable by the opposite end of a dual-function user tool that enables the weight assembly, when unexpanded, to be conveniently moved axially for initial installation, relocation and/or removal.
The above and further objects, features and advantages of the present invention will be more fully understood from the following description taken with the accompanying drawings in which:
A foam sleeve 26 surrounding weight element, and typically attached thereto adhesively, is made and dimensioned to hold the weight assembly 14 concentric in shaft 12 at all times, continuously applying a designated relatively low amount of frictional pressure against the surrounding internal surface of shaft 12.
Foam sleeve 26 is designed and dimensioned to deliver a particular designated amount of frictional pressure radially onto surrounding shaft 12 such that, with expansion element 20 disengaged from shaft 12, the friction is (1) sufficiently high enough to hold weight assembly 14 in place in shaft 12 without rotation while screw 22 is being rotated by driver tool end 28A to deploy/release expansion element 20, and yet (b) sufficiently low enough to allow convenient axial displacement of weight assembly 14 for relocation or removal by user manipulation of tool 28, engaged by threaded driver end 28B as shown in
For installation in original manufacture, aftermarketing and user golf play, weight assembly 14 is initially pre-set to its inherent unexpanded condition by counterclockwise rotation of the tool 28 with its hex driver end 28A engaging screw 22. Then tool 28 is inverted and with end 28B threaded into weight element 18, the weight assembly 14 is inserted into the shaft 12 to the desired location, unexpanded as shown in
For removal or relocation of weight assembly 14, cap 16 (or grip 10) is removed, and tool end 28A is inserted and engaged into screw 22, as shown in
Optionally, the low end of screw 22 can be swaged or crimped as shown in
Optionally, two or more weight assemblies 14 could be installed, as described above, at designated locations in shaft 12, subject to making tool 28 sufficiently long.
In the primary embodiment of the invention, cap 16 (
The range of available working locations of weight assembly 14, extending downward from the top end of shaft 12, is limited by the length of tool 28, typically made approximately 12 inches long, as considered to be adequate for practically all weighting requirements.
Cap 16′ is configured with (a) an externally threaded main portion, as shown, for threaded attachment to the grip 10, (b) a central opening 16A with hex cross-sectional shape (
In the secondary embodiment weight assembly 14′, the approach of adding cap 16′ adhesively attached onto weight element 18, as shown in
As an alternative to attaching cap 16′ to weight element 18, these can be combined into a single component designed to serve as an integrated cap/weight element that is fully equivalent functionally, more rugged structurally, and potentially cost effective, considering the elimination of costs and labor associated with sleeve 26, and eliminating the machining of threading inside the weight element, no longer required due to the designated location of the weight assembly being restricted to the uppermost end region of shaft 12.
The invention can be practiced with materials, details, sizes and proportions of the component parts deviating from those indicated in the drawings of the illustrative embodiments shown. Tools and mating drive receptacles shown and described as hex could optionally be implemented in any other equivalent driver configuration.
This invention may be embodied and practiced in other specific forms without departing from the spirit and essential characteristics thereof. The present embodiments therefore are considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All variations, substitutions, and changes that come within the meaning and range of equivalency of the claims therefore are intended to be embraced therein.
Claims
1. A golf club weighting system for adding a desired amount of swing weight at a designated axial location in a hollow shaft of a golf club equipped with a grip, the system being viable in original manufacture, in after-marketing and in user golf play, implemented by a weight assembly comprising:
- a cylindrical rigid weight element, located coaxially in the hollow shaft, having an outside diameter made smaller than the shaft's inside diameter so as to provide a designated inherent peripheral clearance therebetween;
- a cylindrical expansion element, located coaxially in the hollow shaft beneath said weight element and attached thereto, having an inherent unexpanded outside diameter made smaller than the shaft's inside diameter so as to provide a designated inherent peripheral clearance dimension therebetween whenever said expansion element remains unexpanded; and
- an expansion subsystem in said weight assembly, including a machine screw that is drivable by a user expansion tool to clamp said resilient expansion element against said weight element so as to causing axial compression in said expansion element that translates into radial expansion exerting compressive contact against the surrounding shaft, thus applying thereto a frictional force that that can be increased by the user until said weight assembly becomes positively and reliably secured in place by frictional pressure against the surrounding shaft, thus ensuring fully satisfactory golf play with a desired amount of swing-weight added at the designated axial location.
2. The golf club weighting system as defined in claim 1 wherein said expansion subsystem comprises:
- said weight element being configured with (a) a coaxial bore having a threaded upper portion and a lower portion with reduced diameter, forming a co-axial ledge therebetween, and (b) a tubular-shaped resilient foam sleeve surrounding said weight element and held continuously compressed in contact with the surrounding shaft;
- said expansion element being configured with a coaxial bore and fitted at bottom with a pressure plate having a threaded central opening;
- the machine screw having a screw-head configured with a central driving recess, the screw-head located in the bore of said weight element, seated on the coaxial ledge with a threaded part of the machine screw extending downwardly, through the smaller diameter lower portion of the bore, continuing through the bore of said expansion element and engaging the threaded opening of the pressure plate, whereby tightening the screw clockwise acts to clamp and compress the resilient expansion element between said weight element and said pressure plate causing axial compression in said expansion element that translates into radial expansion exerting compressive contact against the surrounding shaft to frictionally secure said weight assembly in place in the shaft for golf play.
3. The golf club weighting system as defined in claim 2 further comprising a user expansion tool made with a driving end configured to engage and rotate the screw for purposes of deploying expansion of said expansion element so as to secure said weight assembly in place in the shaft by rotating said user expansion tool clockwise and to release the expansion by rotating said user expansion tool counterclockwise.
4. The golf club weighting system as defined in claim 3 further comprising a user location tool being configured with a threaded engagement end made to threadedly engage the threaded bore portion in the weight element, whereby the user is enabled to threadedly attach the tool to the weight assembly and manipulate said user location tool in a manner to displace said weight assembly axially in the shaft for purposes of installing, relocating and removing said weight assembly.
5. The golf club weighting system as defined in claim 4 wherein the tubular-shaped resilient foam sleeve surrounding said weight element is continuously compressed in contact with the surrounding shaft with sufficient friction to retain said weight assembly in place in the shaft whenever said expansion element is unexpanded and to prevent rotation thereof when the screw is being rotated for expansion and release, yet allowing said weight assembly to be displaced axially in the shaft using said user location tool for purposes of installing, relocating and removing said weight assembly.
6. The golf club weighting system as defined in claim 5 wherein the central driving recess in the screw-head and the driving end of said user expansion tool are made hexagonal in cross-sectional shape.
7. The golf club weighting system as defined in claim 5 further comprising:
- an externally threaded grip cap threadedly attached to the grip; and
- a central though-opening in said cap, configured in a standard hex drive cross-sectional shape for purposes of attachment and removal of the cap portion relative to the grip, said though-opening being made sufficiently large to allow insertion of the screw-driving end of said user expansion tool for purposes of securing and releasing the weighting assembly relative to the shaft.
8. The golf club weighting system as defined in claim 2 in an embodiment thereof wherein the designated axial location in the upright hollow shaft of the golf club is at an uppermost top portion thereof.
9. The golf club weighting system as defined in claim 8 wherein said weight assembly further comprises a grip cap, attached onto a top portion of the weight element, configured with a central though-opening sufficiently large to allow insertion of the screw-driving end of said user tool.
10. The golf club weighting system as defined in claim 9 further comprising:
- said grip cap being externally threaded and thereby threadedly attached to the grip; and
- the central though-opening in said cap being configured in a standard hex drive cross-sectional shape for engagement with a standard hex drive tool for purposes of rotating said cap portion along with the attached unexpanded weight assembly for threaded attachment thereof to the grip, and for detachment therefrom.
11. The golf club weighting system as defined in claim 8 wherein said weight assembly further comprises the weight element being configured to further include, in an uppermost region thereof, a grip cap portion configured with a central though-opening sufficiently large to allow insertion of said user location tool for purposes of securing and releasing the weighting assembly relative to the shaft.
12. The golf club weighting system as defined in claim 11 further comprising:
- the grip cap portion being externally threaded and thereby threadedly attached to the grip; and
- the central though-opening in the cap portion being configured in a standard hex drive cross-sectional shape for engagement with a standard hex drive tool for purposes of rotating the unexpanded weight assembly via the cap portion thereof for threaded attachment thereof to the grip, and for detachment therefrom.
13. A method of adding swing weight to be frictionally secured in place at a designated location in a hollow shaft of a golf club, viable in original manufacture, in after-marketing and in user golf play, comprising the steps of:
- (a) attaching a location tool to a weight assembly comprising a weight element held together against an unexpanded resilient expansion element by a machine screw with a screw-head made drivable by an expansion tool;
- (b) deploying the location tool to insert the weight assembly to a designated location in the shaft;
- (c) detaching and withdrawing the location tool from the shaft;
- (d) inserting the expansion tool into the shaft and into driving engagement with the screw-head;
- (e) rotating the screw clockwise by the expansion tool to pressurize and expand the expansion element so as to apply increasing pressure force peripherally against the surrounding shaft until the weight assembly has been frictionally secured in place; and
- (f) withdrawing the expansion tool from the shaft.
14. The method of claim 13 continued to later move the weight assembly to another location in the shaft, comprising the further steps of:
- (g) inserting the expansion tool into the shaft and into driving engagement with the screw-head;
- (h) rotating the screw counterclockwise by the expansion tool to depressurize and release the expansion element from contact with the shaft;
- (i) withdrawing the expansion tool from the shaft;
- (j) inserting the location tool into the shaft and engaging the weight element;
- (k) moving the weight assembly to the different location in the shaft by manipulation of the location tool;
- (l) withdrawing the location tool from the shaft;
- (m) inserting the expansion tool into the shaft and into driving engagement with the screw-head;
- (n) rotating the screw clockwise by the expansion tool to pressurize and expand the expansion element so as to secure the weight assembly in place in the different location; and
- (o) withdrawing the expansion tool from the golf club.
15. The method of claim 13 continued to later remove the weight assembly from the golf club, comprising the further steps of:
- (p) inserting the expansion tool into the shaft and into driving engagement with the screw-head;
- (q) rotating the screw counterclockwise by the expansion tool sufficiently to depressurize and release the expansion element from contact with the shaft;
- (r) withdrawing and removing the expansion tool from the golf club;
- (s) inserting the location tool into the shaft and engaging the weight element; and
- (t) removing the weight assembly from the golf club shaft by manipulation of the location tool.
16. A method of adding a weight assembly within a hollow shaft of a grip-equipped golf club at a designated location restricted to an uppermost portion of the shaft, secured in place by the combination of (1) an expansion element capable of frictionally engaging the shaft and (2) a cap portion atop the weight assembly, threadedly engaging the grip, viable in original manufacture, in after-marketing and in user golf play, comprising the steps of:
- (a) configuring the weight assembly including a cylindrical weight element, smaller in diameter than the shaft interior, combined with an overhead externally-threaded annular grip cap portion larger in diameter than the weight element, and an underlying resilient expansion element, deployable via a screw-head made accessible and engagable by a user expansion tool to be expanded radially so as to frictionally secure the weight assembly in place in the shaft;
- (b) configuring the grip with a top central grip opening sized and internally threaded to engage the cap portion;
- (c) inserting the weight assembly, unexpanded, through the grip [opening into the top of the shaft, until the cap portion is aligned for threaded attachment to the grip;
- (d) inserting a cap drive tool into engagement with a driving recess in the cap portion;
- (e) rotating the weight assembly, by the cap drive tool, to thread the cap portion fully into the grip thus placing the weight assembly in the designated uppermost location in the shaft;
- (f) removing the cap drive tool from the golf club;
- (g) inserting the expansion tool into engagement with the screw-head;
- (h) rotating the expansion tool and screw-head clockwise until the expansion element displaces the weight assembly axially in the shaft for purposes of installing, relocating and removing the weight assembly; and
- (i) removing the expansion tool from the golf club.
17. The method of claim 16 continued to later remove the weight assembly from the golf club, comprising the further steps of:
- (j) inserting the expansion tool into engagement with the screw-head;
- (k) rotating the expansion tool and screw counterclockwise so as to relax the expansion element until the weight assembly becomes released from contact with the shaft;
- (l) removing the expansion tool from the golf club;
- (m) engaging the cap portion with the cap drive tool and rotating the weight assembly thereby so as to unthread the cap portion fully from the grip thus releasing the weight assembly from the grip;
- (o) removing the cap drive tool from the golf club;
- (p) removing the weight assembly from the golf club; and
- (q) restoring the grip to a playable condition including closure of the grip opening.
Type: Application
Filed: Apr 22, 2016
Publication Date: Oct 26, 2017
Inventor: John Johnson (Ojai, CA)
Application Number: 15/136,822