Abstract:
The golf club head with an adjustable center of mass provides for player adjustment of club action according to the position of an adjustable weight or mass within the club head. A hollow, “metal wood” type club head includes an open receptacle in the sole wall, with an L-shaped arm and mass installing in the receptacle. The arm includes a club head attachment end that attaches within the receptacle, and a weighted end, which extends into the interior of the club head. The L-shaped arm may be turned about its mounting axis to orient the weight or mass to the front, rear, left, or right within the club head, or to some intermediate position therebetween. The adjustably positionable mass alters the collective center of gravity of the assembly to affect the draw, fade, and loft tendencies of the club, as well as affecting the vibratory characteristics of the club.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to equipment and implements used in the game of golf. More particularly, the present invention relates to a golf club head with an adjustable center of mass.  
         [0003]     2. Description of the Related Art  
         [0004]     As the game of golf has become more popular, more has been learned about the various subtleties and nuances involved in its play. All golfers use clubs of two basic types in order to optimize their play, i.e., “irons” and so-called “woods,” named for the historic compositions of their club heads. Irons were, and still are, formed of a ferrous metal, with stainless steel being a common material in modern clubs. “Woods” were historically formed of a solid mass of wood (persimmon wood being a popular choice) with somewhat larger and often more massive weighted club heads than irons for use in driving the ball from the tee.  
         [0005]     More modern “wood” club heads are usually not formed of wood at all, but are often formed of thin wall, hollow metal castings or forgings. Such club heads are generally called “metal woods,” as they have the external configuration of a historic wood club head while being constructed of metal. The use of metal in the construction of such club heads provides numerous advantages in strength and durability, and the hollow head allows various masses to be installed within the club head in order to affect its performance.  
         [0006]     In the past, various club manufacturers have made numerous attempts to “fine tune” the action of a metal wood type club, by installing various weights and masses within the club head. Generally, these masses were immovably affixed within the head, thus allowing no further tuning or adjustment of the effect of the added weight or its position within the head of the club. A few manufacturers have provided for movable or adjustable weights within the club head in order to seek the potential advantages that might be provided by such a configuration.  
         [0007]     An example of a golf club head having a movable weight is illustrated in French Patent No. 2,716,808, published on Sep. 8, 1995. A mallet-type golf putter is illustrated, having opposed lateral bores to each side of the central club shaft attachment. Weights may be installed in the bores adjacent to the central shaft attachment area of the club head to affect the balance of the putter. The weights are held in place by springs installed outboard of the weights, holding the weights inwardly toward the attachment end of the shaft. No rotary adjustable weight about a vertical axis is apparent.  
         [0008]     Japanese Patent No. 11-197,276, published on Jul. 27, 1999, illustrates a metal wood-type club head having a pocket or receptacle welded in place to the sole plate within the club head. A weld-resistant metal is placed within the receptacle, prior to welding. No adjustment of the location or quantity of the weight is possible after installation.  
         [0009]     Finally, Japanese Patent No. 2004-121,362 published on Apr. 22, 2004, illustrates further variations on a metal wood-type club head having a fixed, non-adjustable weight or mass installed therein.  
         [0010]     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a golf club head with an adjustable center of mass solving the aforementioned problems is desired.  
       SUMMARY OF THE INVENTION  
       [0011]     The golf club head with adjustable center of mass includes a generally L-shaped arm having a club head attachment end and an opposite mass attachment end. An open socket or receptacle is provided in the sole of the club head, into which the club head attachment end of the arm seats. A cover plate is installed over the end of the arm and within the socket in order to preclude capture of dirt and debris within the socket during use of the club and to clamp the mass arm tightly within the receptacle. A series of detents is provided within the socket, with the attachment end of the arm having a mating configuration in order to lock the arm at the desired one of a series of specific angles or positions in the detents.  
         [0012]     The arm may be adjusted to face forwardly, rearwardly, or to the left or right relative to the club face, or at some intermediate position between any of the above cardinal positions, to adjust the action of the club. Orienting the mass toward the hosel and shaft of the club places the mass of the club head between the center of the club and hosel, and results in a hook or draw (or correction of the opposite slice or fade). Positioning the mass in the opposite direction will, of course, have the opposite effect. Positioning the mass toward the front of the club head results in a lower loft or arcuate flight of the ball when struck, while positioning the mass toward the rear of the club head has the opposite effect. The arm also affects the vibrational characteristics of the club, depending upon the materials from which the arm and its weight are formed.  
         [0013]     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is an exploded perspective view of the golf club head with adjustable center of mass according to the present invention, showing the separation of the arm and weight from the club head.  
         [0015]      FIG. 2A  is a front elevation view of the golf club head of the present invention showing the initial position of the weight and arm during installation into the club head.  
         [0016]      FIG. 2B  is a front elevation view of the golf club head of the present invention showing an intermediate position of the weight and arm during installation into the club head.  
         [0017]      FIG. 2C  is a front elevation view of the golf club head of the present invention showing the nearly completed installation of the weight and arm into the club head.  
         [0018]      FIG. 3  is a detailed, exploded bottom plan view of the arm and mass of the golf club head of the present invention.  
         [0019]      FIG. 4  is a bottom plan view of the adjustable mass club head of the present invention, showing a series of cardinal positions for the adjustably positionable arm and mass therein.  
         [0020]      FIG. 5  is a top plan view of the golf club head of the present invention, showing the twisting effects on the club head and shaft during a swing when the weight is oriented laterally.  
         [0021]      FIG. 6  is a side elevation view of the golf club head of the present invention showing the rearward positioning of the adjustable weight and corresponding bending of the shaft during a swing.  
     
    
       [0022]     Similar reference characters denote corresponding features consistently throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The present invention is a hollow golf club head having an adjustably positionable mass therein, providing the club head with an adjustable collective center of mass. The adjustable center of mass is used to adjust the loft, draw (hook) and fade (slice) tendencies of the club and golfer combination during play.  
         [0024]      FIG. 1  of the drawings is an exploded perspective view of a hollow “metal wood” club head  10  of the present invention, i.e., a club head formed as a hollow, thin wall metal casting, but having the form of a conventional wood club head (e.g., driver, three wood, etc.) that would otherwise be formed of an essentially solid block or laminates of wood. Accordingly, the club head  10  includes a bottom or sole plate  12 , a club face  14  at the front of the club head  10 , a rear club head portion  16 , a heel portion  18  having a club shaft hosel  20  extending therefrom, and a toe portion  22  opposite the heel portion  18 . These various portions of the club head  10 , along with the closed upper surface or wall of the club head  10 , define a hollow interior  24  for the club head  10 .  
         [0025]     The hollow interior of the club head  10  is normally closed, but is accessible by an open weight installation receptacle passage  26  formed through the sole plate  12  of the club head. The receptacle passage  26  includes a recessed annular flange  28  surrounding the passage and extending inwardly toward the center of the passage  26 . The flange  28  includes at least one detent  30  thereon, serving to lock the position of the adjustably positionable mass relative to the club head  10 , as explained further below. The larger diameter portion  32  of the receptacle  26  is threaded to accept a matingly threaded receptacle cap  34  therein, with the cap  34  also securing an adjustably positionable mass immovably within the club head  10 . The cap  34  is configured to have its exterior surface disposed essentially flush with the sole plate  12  of the club head  10  when the adjustable mass and cap  34  are properly secured in the club head.  
         [0026]     A series of index markings, e.g.,  36   a  through  36   f  (more or fewer may be provided), may be provided surrounding the receptacle  26  on the sole plate  12  surface of the club head  10 . Corresponding legends, e.g.,  38   a  through  38   d  (more or fewer may be provided), are also provided surrounding the receptacle  26  and index markings  36   a  through  36   f , to indicate the proper orientation of the adjustably positionable mass within the club head  10  in order to achieve the desired effect or result.  
         [0027]     An adjustably positionable rotary mass  40  is removably installed within the club head  10  through the weight installation receptacle  26 . The rotary mass  40  has a unitary, monolithic, generally L-shaped configuration, with a club head attachment leg  42  and club head attachment end  44 , and an opposite weighted leg  46  and weighted end  48 . The weighted leg  46  and its end  48  are cantilevered from the club head attachment leg  42  and end  44 , and describe a circular path within the hollow interior volume  24  of the club head  10  as the club head attachment end  44  is adjustably rotated within its club head receptacle  26 .  
         [0028]     The club head attachment end  44  of the L-shaped rotary mass  40  is configured to fit closely within the base of the mass or weight installation receptacle  26 , adjacent the inset flange  28 . The club head attachment end  44  of the mass arm  40  has a generally circular configuration, with a series of circumferentially disposed notches  50  that engage the detent or detents  30  of the flange  28 . Preferably, several evenly spaced notches  50  are provided, allowing the mass  40  to be positioned in any of several orientations within the club head  10  radiating from the weight installation receptacle  26 .  
         [0029]      FIGS. 2A through 2C  illustrate the installation of the L-shaped rotary mass  40  within the club head  10 . In  FIG. 2A , the weighted leg  46  of the mass  40  has been inserted through the receptacle opening or passage  26  and partially into the hollow interior volume  24  of the club head  10 . As the L-shaped weight or mass  40  is inserted further into the interior  24  of the club head  10 , it is turned as the elbow of the device, i.e., the juncture of the two legs  42  and  46 , passes through the opening  26 . The mass arm  40  is finally installed in the position shown in broken lines in  FIG. 6 , with the weighted leg  46  generally parallel to the sole plate  12  of the club head and the club head attachment leg  42  extending inwardly into the club head  10  and generally normal to the sole plate  12 .  
         [0030]      FIG. 3  provides an exploded detail plan view of the rotary weight or mass  40  of the device, including a plan view of the club head attachment end or flange  44 . The club head attachment end  44  of the device, with its radial array of notches  50 , which selectively engage the detents  30  at the base of the receptacle  26 , are clearly shown in  FIG. 3 . While an array of twelve notches  50  is shown, providing twelve different angular positions for the weight arm  46  separated radially by thirty degrees each, it will be seen that more or fewer such notches may be provided for finer or more coarse positional adjustment of the weight  40 , as desired.  
         [0031]     It will be noted that a positional indicator  52  is disposed across the external face of the club head attachment end  44  of the rotary mass  40 . The indicator  52  is preferably aligned with the weight leg  46  of the device  40 , so a golfer may determine at a glance the orientation of the weight leg  46  within the hollow volume  24  of the club head  10 . The indicator  52  will point toward one of the legends  38   a  through  38   d  disposed upon the sole plate  12  of the club head  10 , and/or align with one of the index markings  36   a  through  36   f , when the club head attachment end or flange  44  is securely seated in the receptacle  26  of the club head  10 . This allows the golfer to readily determine the orientation of the weighted leg  46  within the club head  10 , and to judge the corresponding characteristics of the club produced by a given orientation of the mass arm  40  within the club head  10 .  
         [0032]     While the weight or mass arm  40  itself is formed as a unitary, monolithic component, adjustment of the mass may be provided by adjustably or removably affixing an additional weight or mass  54  to the weighted leg end  48  of the device. The weighted leg  46  includes a concentric internally tapered threaded passage  56 , with the supplemental weight  54  having a correspondingly tapered threaded shank  58  extending from its head  60 . The threaded shank  58  of the supplemental weight  54  is secured within the threaded passage  56  of the weighted leg  46  of the rotary mass or arm  40  and adjusted as desired to provide a longer or shorter overall leg length, and thus a greater or smaller moment, for the weighted leg  46  and supplemental mass  54 . It will be seen that further adjustment may be achieved by using different supplemental masses, or by adding or removing washers or spacers (not shown) between the head  60  of the supplemental weight  54  and the weight leg end  48  of the rotary mass  40 , as desired.  
         [0033]     The above described mass arm  40  and its supplemental weight or mass  54  may also provide benefits in the control of vibration of the club head and shaft during a golf stroke, as well as having an effect on the angle of the club face  14  when the ball is struck. It will be seen that the hollow club head  10  and its shaft (not shown), particularly in combination with the adjustably positionable cantilevered mass arm  40 , will have certain vibration or resonance characteristics. These resonance or vibration characteristics may be controlled or affected by adjusting the material from which the rotatable mass arm  40  is formed, and/or coating the arm  40 , or at least the weighted leg portion  46 , with a vibration damping coating  62  (e.g., plastic of predetermined density and hardness, etc.) Plastic or other suitable coating material may be used where the mass  40  is formed of metal, or alternatively the entire mass  40  may be formed of a unitary, monolithic vibration damping material, as desired.  
         [0034]      FIG. 4  provides a schematic bottom plan view of the present golf club head  10 , showing a series of four different positions for the adjustable mass arm component  40  therein and corresponding shift in the center of gravity of the club head  10 . The original center of gravity, CG 0 , is shown aligned with the club head hosel  20 . However, the installation and adjustment of the adjustably positionable mass  40  of the present invention will shift the collective center of gravity of the club head  10 , and thus the entire head and shaft assembly of the club, depending upon the orientation of the weighted leg  46 . If the weighted leg of the adjustable mass is oriented forwardly, i.e., toward the club face  14 , as indicated by weighted leg position  46   1 , the collective center of gravity of the club head and mass assembly is also shifted by a corresponding amount to a slightly forward location at CG 1 . Alternatively, if the mass arm is turned 180° toward the back  16  of the club head to the position indicated by leg  46   2 , the center of gravity is shifted by a corresponding amount to approximately the position shown as CG 2 . Similar changes occur when the weighted leg is shifted toward the heel  18  or toe  22  of the club head  10 , with the heel orientation of the weighted leg shown as  46   3  and its corresponding center of gravity at CG 3 , and the toe orientation of the leg shown as  46   4  and corresponding center of gravity at CG 4 . Greater or lesser displacements of the center of gravity may be provided, depending upon the mass of the weighted leg  46  and its supplemental weight (if any), and the mass of the club head  10  and its shaft, particularly near the hosel  20 .  
         [0035]      FIG. 5  of the drawings provides a top plan view of the club head  10 , showing the effects of the club heel or club toe orientation of the mass arm on the fade and draw (slice and hook) characteristics of the club. In  FIG. 5 , two alternative positions are shown for the weighted leg, i.e., inwardly toward the heel  18  or hosel  20  of the club head  10 , as weighted leg position  46   3 , and outwardly toward the toe portion  22  of the club head  10 , as weighted leg position  46   4 . These two weighted leg positions  46   3  and  46   4  are equivalent to the positions  46   3  and  46   4  shown in  FIG. 5  of the drawings.  
         [0036]     When the mass arm is turned inwardly to the position shown as weighted leg  46   3  in  FIG. 5 , the collective mass of the club head and adjustable mass is shifted slightly inward, i.e., toward the heel  18  and hosel  20  of the club head  10 . The greater mass to the inboard portion of the club head  10  results in a tendency for that portion of the club head to lag slightly behind the outer portion of the club head as the golfer accelerates the club head during the swing. This causes the club face to be turned slightly inward, i.e., toward the golfer, during the accelerating portion of the swing, as indicated by the displaced club face position  14   3  shown in broken lines in  FIG. 5 . (The angular displacement of the club face due to this effect is greatly exaggerated in  FIG. 5 , for clarity in the drawing Fig.) This adjustment can be quite valuable for a golfer who has a tendency to slice or fade the ball, i.e., to strike the ball to produce a flight path angling to the right of the ideal path (for a right-handed golfer).  
         [0037]     When the mass arm is turned outwardly toward the toe  22  of the club head  10 , as shown by the weighted leg position  46   4  in  FIG. 5 , a generally opposite result occurs. The shifting of the center of gravity of the club head and mass assembly toward the outer portion or toe of the club head  10 , as indicated by the center of gravity position CG 4  in  FIG. 5 , causes the outer portion of the club head  10  to lag slightly as the club is accelerated in its swing. This results in the club face  14  being turned slightly outwardly away from the golfer, somewhat as shown by the displaced face position  14   4  in  FIG. 5 . It will be seen that this serves to correct a tendency for a golfer to hook or draw the ball, i.e., strike the ball to produce a flight path to the left of the desired path (for a right-handed golfer).  
         [0038]     The effects are somewhat different when the weighted leg  46  is adjusted to a forwardly or rearwardly disposed position within the club head. The effect of the rearward adjustment of the weighted arm is shown in  FIG. 6  of the drawings, with forward adjustment producing an opposite effect. In  FIG. 6 , the weighted leg has been adjusted rearwardly within the club head  10 , to a position  46   2  as shown in  FIGS. 4 and 6 . This results in the adjustment of the center of gravity rearwardly in the club head to the new center of gravity position CG 2 , rearward of the axis of the club shaft S.  
         [0039]     When the club is swung, centrifugal force shifts the center of gravity CG 2  radially outwardly by a small displacement D 1 . As the new center of gravity CG 2  is not aligned with the axis of the club shaft S, this has the effect of lowering the rear of the club head  10 . As the forward portion of the club head  10  is immovably affixed to the shaft S, the result is a slight bending of the club shaft S, causing the club shaft S and club head  10  to shift forwardly by a displacement D 2  and take the position shown in broken lines in  FIG. 6 . (The bending of the club shaft S and altered position of the club head  10  in broken lines, are greatly exaggerated in  FIG. 6  for clarity in the drawing.)  
         [0040]     This bending of the club shaft S shifts the angle of the club head  10 , and thus the club face  14 , relative to the upper portion of the club shaft S. The forward displacement of the club head  10  relative to the upper portion of the club shaft S results in an angular displacement of the club face  14 , altering the dynamic loft angle L of the club face to the slightly shallower angle shown in broken lines. (Again, the various displacement effects are greatly exaggerated for clarity.) Adjustment of the weighted leg to a forward position within the club head  10  will be seen to produce the opposite effect, i.e., to reduce the effective dynamic loft angle of the club. This adjustability can be of great assistance to a golfer who requires a club having a loft angle between two standard clubs, and/or who wishes to eliminate certain clubs from his golf bag by providing a single universal metal wood club that is adjustable for different characteristics.  
         [0041]     In conclusion, the present golf club head with its adjustable center of mass is a most useful addition to the collection of clubs owned and used by the serious golfer. A golfer who has a consistent tendency to draw or fade the ball, particularly from the tee, can adjust such tendencies out of his or her swing by means of the adjustability of the present club. Moreover, the golfer may adjust the effective or dynamic loft of the present club to make fine adjustments thereto, perhaps finding that carrying an intermediate club (e.g., a two wood) equipped with the present adjustable center of mass may be used to replace the conventional driver and three wood as well. The golfer need only remove the protective cap from the weight receptacle, adjust the radial position of the adjustable mass according to the index markings and legend on the sole plate of the club head, and replace the cap to secure the mass in the desired position. This adjustability and versatility of the present club will be most appreciated by golfers of virtually all levels of skill and expertise.  
         [0042]     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.