Abstract:
A golf club head with a variable center of gravity is disclosed herein. More specifically, the present invention discloses a wedge type golf club head wherein the center of gravity of the golf club head is adjustable along an x-axis in a heel to toe direction utilizing weights that are placed substantially near a sole portion of the golf club head. The resulting golf club head may generally have a more toe biased center of gravity location, especially when compared to a traditional golf club head.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a golf club head with variable center of gravity. More specifically, the present invention relates to a wedge type golf club head wherein the center of gravity of the golf club head is adjustable along an x-axis in a heel to toe direction utilizing weights that are placed substantially near a sole portion of the golf club head. The weight, in one exemplary embodiment of the present invention, may be placed within a cavity that is formed at the bottom sole portion of the golf club head, while other embodiments may place the weights at different locations inside or even outside of the cavity to achieve different center of gravity locations. 
       BACKGROUND OF THE INVENTION 
       [0002]    In order to improve the performance of a golf club head, golf club designers have been utilizing weighting members to adjust the center of gravity location of the golf club head. U.S. Pat. No. 2,067,556 to Wettlaufer from back in 1937 provides one of the earlier illustrations of this idea by disclosing a golf club head with a plurality of ducts extending into the club head to accommodate bodies of mercury, which alter the weight of the golf club head and adjusts the center of gravity. 
         [0003]    U.S. Pat. No. 7,771,291 to Willett et al. issued in 2010 illustrates a modern day version of a weight adjustment mechanism for altering the center of gravity in a metalwood type golf club head. U.S. Pat. No. 7,771,291 to Willett teaches a golf club head that includes at least one weight port situated to retain weights and positioned above an approximate club face geometric center. The patent goes on to show that weights can then be applied to the weight ports in different variations, allowing an adjustment to the center of gravity of the golf club head. 
         [0004]    Although the bigger chassis of a wood or metalwood type of golf club head makes it a more preferred chassis for using weights to adjust the center of the golf club&#39;s center of gravity, adjustment of the center of gravity can also be accomplished in an iron type golf club head having a smaller chassis as well. U.S. Pat. No. 6,015,354 to Anh et al. issued back in 2000 provides an illustration of a weighting system used to adjust the center of gravity of an iron type golf club head. More specifically, U.S. Pat. No. 6,015,354 discloses a golf club head having built-in provisions to change the weight of the golf club head including a way to increase, decrease, or adjust the position and the amount of weight in a selected golf club head to enable the player to adjust the club&#39;s center of gravity. 
         [0005]    In fact, the idea of using weights for adjusting the center of gravity of a golf club head is so prevalent, it can even extend to wedge type golf club head as shown in U.S. Pat. No. 7,309,295 to Solari back in 2007. U.S. Pat. No. 7,309,295 teaches a golf club head for a chipper or wedge that provides a large striking area as well as selectable weight distribution. The golf club head has an open interior cavity having an enclosed lid enabling the permanent or removable fixation of weights for selectable weight distribution. 
         [0006]    Although there are numerous attempts in the past of using weights to adjust the center of gravity of a golf club head, none of these methods focus on a way to adjust the center of gravity in a way that truly benefits a wedge type golf club head. Because the wedge is such a precise club in a golfer&#39;s arsenal, the precise center of gravity location along the x-axis, y-axis, and z-axis are all critical in its ability to perform as needed. More specifically, in the current art, there is no wedge type golf club head that allows for the center of gravity adjustment described above to be accomplished in a cleaner and aesthetically pleasing manner. 
         [0007]    Hence, as it can be seen from above, despite all the attempts in creating a golf club having an adjustable center of gravity, none of them are capable of applying them to a wedge type golf club head in a manner that is clean, effective, and aesthetically pleasing. Ultimately, it can be seen from above that there is a need in the art for a wedge type golf club head capable of providing the center of gravity adjustment in the x, y, and z-orientations in an effective and clean way. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    One aspect of the present invention is a wedge type golf club head comprising of a striking face portion located at a frontal portion of the wedge type golf club head; a backing portion located behind the striking face portion; and a sole muscle portion located at a bottom of the wedge type golf club head between the striking face portion and the backing portion, wherein the sole muscle portion further comprises a cavity having an opening and one or more weights shaped to at least partially fit in the cavity, and wherein the wedge type golf club head has a center of gravity greater than about  28  mm from an intersection point between a hosel bore axis and a ground plane along an x-axis. 
         [0009]     Another aspect of the present invention is a golf club head comprising of a striking face portion located at a frontal portion of the golf club head; a backing portion located behind the striking face portion; and a sole muscle portion located at a bottom of the wedge type golf club head between the striking face portion and the backing portion, wherein the sole muscle portion further comprises a cavity having an opening and one or more weights shaped to at least partially fit in said cavity, and wherein the opening of said cavity is opened towards a bottom sole portion of the sole muscle portion. 
         [0010]    A further aspect of the present invention is a golf club head comprising of a striking face portion located at a frontal portion of the golf club head; a backing portion located behind the striking face portion; a sole muscle portion located at a bottom of the wedge type golf club head between the striking face portion and the backing portion, a weight pocket located at an upper toe portion of the backing portion of the golf club head, and a weight pad, located congruently within the weight pocket, wherein the wedge type golf club head has a center of gravity greater than about 28 mm from an intersection point between a hosel bore axis and a ground plane along an x-axis. 
         [0011]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    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. 
           [0013]      FIG. 1  shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0014]      FIG. 2  shows an exploded perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0015]      FIG. 3  shows a perspective view of an internal structure of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0016]      FIG. 4  shows a frontal view of a golf club head in accordance with an exemplary embodiment of the present invention; 
           [0017]      FIG. 5  shows a perspective view of an internal structure of a golf club head in accordance with an alternative embodiment of the present invention; 
           [0018]      FIG. 6  shows a perspective view of an internal structure of a golf club head in accordance with a further alternative embodiment of the present invention; 
           [0019]      FIG. 7  shows a perspective view of a golf club head in accordance with another alternative embodiment of the present invention; 
           [0020]      FIG. 8  shows an exploded perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
           [0021]      FIG. 9  shows a perspective view of a golf club head in accordance with a further alternative embodiment of the present invention; 
           [0022]      FIG. 10  shows a perspective view of a golf club head in accordance with a further alternative embodiment of the present invention; and 
           [0023]      FIG. 11  shows a perspective view of a golf club head in accordance with a further alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    The following detailed description describes 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. 
         [0025]    Various inventive features are described below and each can 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. 
         [0026]      FIG. 1  of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an exemplary embodiment of the present invention. The golf club head  100  may generally have a striking face portion located at a frontal portion of the golf club head  100 , a backing portion located just behind the striking face portion. The golf club head  100  may have a sole portion  102  located near a bottom “muscle portion” of the golf club head  100  and a topline portion  104  located near a top of the golf club head  100 .  FIG. 1  also shows the golf club having a heel portion  103  near the hosel of the golf club head  100  as well as a toe portion  105  near the extremity of the golf club head  100 . The golf club head  100  in accordance with the present invention may generally have a cavity near the sole portion  102  of the golf club head where it can accommodate one or more weight members at different locations within the cavity. Because  FIG. 1  shows a finished golf club head  100 , the cavity is covered by up a cover  106 , concealing the cavity and any weight members intended for the cavity itself. The cover  106  as shown in this current exemplary embodiment, may generally have a perimeter that is slightly smaller than the perimeter of the cavity itself, allowing room for welding material to be applied to attach the cover to the sole muscle portion of the golf club head  100 . Finally,  FIG. 1  also shows a weight pocket  108  located near an upper toe portion of the golf club head  100  near the back of the topline  104  of the golf club head  100 . The weight pocket  108  shown in this embodiment may generally be filled with an externally exposed weight pad  110  to further help adjust the center of gravity of the golf club head  100 . Alternatively speaking, it can be said that the weight pad  110  is located congruently within the weight pocket  108  to help adjust the center of gravity of the golf club head  100 . 
         [0027]    Before engaging in any further discussion regarding the structure of the golf club head, it is important here to recognize the coordinate system  101  shown in  FIG. 1 . The coordinate system  101  allows the orientation of the golf club head  100  to be defined, as well as setting the stage for subsequent definition of the moment of inertia about certain axis. For the purpose of this invention, the x-axis may generally refer to an axis that coincides with a heel to toe direction of the golf club head  100 . The y-axis, as shown by coordinate system  101  may generally refer to the axis that goes from the top to the bottom of the golf club head  100 . Finally, the z-axis may generally refer to the orientation that goes forward and backwards from the striking face portion of the golf club head  100 . 
         [0028]      FIG. 2  of the accompanying drawings shows an exploded view of a golf club head  200  in accordance with an exemplary embodiment of the present invention. The exploded view of the golf club head  200  allows the cavity  212  and the weight member  214  to be shown more clearly. It should be noted that in this exemplary embodiment, the weight member  214  is located near a toe portion of the golf club head  200  within the cavity  212  to promote a more toe biased center of gravity location. However, in alternative embodiments to be shown later, the weight member  214  could be placed near a heel portion of the cavity or a central portion of the cavity all without departing from the scope and content of the present invention. In fact, in certain embodiments, more than one weight member  214  may even be used within the cavity  212  to achieve a desired center of gravity location without departing from the scope and content of the present invention. 
         [0029]    The exploded view of the golf club head  200  also shows the weight pocket  208  as well as the weight pad  210 . Based on the location of the weight pocket  208  and weight pad  210 , it can be seen that the weight pad  210  can serve to help shift the center of gravity further towards the toe portion of the golf club head  200  while at the same time raising the center of gravity higher along the y-axis. The exploded view of the golf club head  200  also shows that in the current exemplary embodiment of the present invention, the weight pad  210  may generally be secured into the weight pocket  208  via a plurality of two or more screws  216 . In alternative embodiments of the present invention, the weight pad  210  may be attached to the weight pocket  208  via only one screw  216 , via any other mechanical locking process, via a welding process, via a swaging process, or any other process capable of retaining the weight pad  210  without departing from the scope and content of the present invention. 
         [0030]      FIG. 3  of the accompanying drawings shows a golf club head  300  in accordance with an exemplary embodiment of the present invention wherein the cover is removed to show the exact location of the weight member  314  within the cavity  312 . The body portion of the golf club head  300  may generally be made out of steel type material with a density of approximately 7.8 g/cm 3 ; however, numerous other materials that are have a density less than 7.8 g/cm 3  such as aluminum, titanium, or the like without departing from the scope and content of the present invention. In this exemplary embodiment of the present invention, the weight member  314  may generally fit towards the toe portion of the golf club head  300 , while leaving the remaining portion of the cavity hollow once the cap is placed back on. Having the weight member  314  towards the toe portion of the golf club head  300  may improve the performance of the golf club head by creating a more toe biased center of gravity location along the x-axis. Weight member  314 , as shown in this current exemplary embodiment may generally be made out of a high density material such as tungsten with a density of greater than about 17 g/cm 3 . However, numerous other high density materials could be used depending on the desired center of gravity adjustment without departing from the scope and content of the present invention so long as it has a density greater than or equal to that of the body portion of the golf club head  300 . 
         [0031]    In the current exemplary embodiment of the present invention, the portion of the cavity  312  that is not occupied by the weight member  314  may generally remain empty and hollow to accentuate the effects of the weight member  314  in shifting the center of gravity location of the golf club head  300 . However, in alternative embodiments of the present invention, the unoccupied portion of the cavity  312  may be filled with a lightweight material such as a polymer, aluminum, or any other material so long as the material has a density that is lower than that of the weighted member  314  without departing from the scope and content of the present invention. 
         [0032]    In addition to the weight member  314 , the weight pad  310  may generally also be comprised out of a high density tungsten material with a density of greater than about 17 g/cm 3 . Similar to the above, the exact material of the weight pad  310  is not critical, so long as it has a higher density than the body portion of the golf club head  300 . 
         [0033]    The exemplary golf club head, due to the extreme placement of the weight member  314 , may also have an improved performance in the moment of inertia numbers. For example, the current inventive golf club head may have a moment of inertia about the x axis of greater than about 105 kg-mm 2 , a moment of inertia about the y axis of greater than about 320 kg-mm 2 , a moment of inertia about the z axis of greater than about 310 kg-mm 2 , and a moment of inertia about the shaft axis of greater than about 775 kg-mm 2 . 
         [0034]    In addition to the moment of inertia numbers above, the current inventive golf club head may have a center of gravity that is significantly different from any prior art golf club head. In order to illustrate this center of gravity location,  FIG. 4  is provided illustrating a frontal view of the golf club head  400  from its address position. This frontal view of the golf club head  400  allows the center of gravity  422  to be shown more clearly, as it relates to the intersect between the hosel bore axis  423  and the ground  420 . The hosel bore axis  423  may generally relates to the axis centered within the bore of the hosel, and the hosel bore axis  423  intersects the ground  420  at the intersection point  425 . The angle α formed between the hosel bore axis  423  and the ground  420  may generally signify the lie angle of the golf club head  400 , which in terms of most wedge type golf club heads generally be about 64 degrees. In another words, the lie angle α of the current inventive golf club head  400  may generally be about 64 degrees without departing from the scope and content of the present invention. 
         [0035]    The center of gravity  422  location, as measured from the distance of the intersection point  423  along the x-axis, may generally be at a distance d 1  of greater than about 28 mm, more preferably greater than about 30 mm, and more preferably greater than about 33 mm. The center of gravity along the y-axis may generally be at a distance d 2  of greater than about 20.5 mm above a ground plane  420 , more preferably greater than about 21.5 mm above the ground plane  420 , and most preferably greater than about 22.5 mm above the ground plane  420 . 
         [0036]    Having a center of gravity  422  location that is further away from the intersection point  425  may generally be a result of the extreme weighting that is accomplished by the current inventive golf club head  400 . In a conventional golf club head, because so much weight is occupied by the hosel portion, the center of gravity  422  may generally be very close to the intersection point  425 . However, in the current inventive golf club head  400 , due to the extreme weighting shown in the prior figures, the center of gravity  422  may generally be further away from the intersection point  425  both along the x-axis and the y-axis. 
         [0037]      FIG. 5  of the accompanying drawings shows a perspective view of an alternative embodiment of the present invention wherein the cover is removed to show an alternative location of the weight member  514  within the cavity  512 . It can be seen that the embodiment of the present invention shown in  FIG. 5  is different from the embodiment shown in  FIG. 3  because the placement of the weight member  514  is placed closer to the central portion of the sole, hence promoting a golf club head  500  with a more centralized center of gravity location. In this exemplary embodiment of the present invention, the golf club head may have a moment of inertia greater than about the x-axis of greater than about 100 kg-mm 2 , a moment of inertia about the y-axis of greater than about 300 kg-mm 2 , a moment of inertia about the z-axis of greater than about 300 kg-mm 2 , and a moment of inertia about the shaft axis of greater than about 700 kg-mm 2    
         [0038]      FIG. 6  of the accompanying drawings shows a perspective view of a further alternative embodiment of the present invention wherein the cover is removed to show an alternative location of the weight member  614  within the cavity  612 . In this embodiment of the present invention the placement of the weight member  614  may be biased towards the heel portion of the golf club head  600 . In this exemplary embodiment of the present invention, the golf club head may have a moment of inertia about the x-axis of greater than about 100 kg-mm 2 , a moment of inertia about the y-axis of greater than about 300 kg-mm 2 , a moment of inertia about the z-axis of greater than about 300 kg-mm 2 , and a moment of inertia about the shaft axis of greater than about 680 kg-mm 2    
         [0039]    In addition to the above, it can be seen that the weight member  614  could be comprised of a plurality of two or more weight pieces depending on the desired center of gravity change without departing from the scope and content of the present invention. In fact, in alternative embodiments of the present invention multiple weight pieces can be used to create the weight member  614  at different locations within the cavity  612  even if they are not concentrated at a specific location within the cavity  612 . 
         [0040]      FIG. 7  of the accompanying drawings shows a perspective view of a golf club head  700  in accordance with a further alternative embodiment of the present invention wherein the cavity  712  is located near the back side of the golf club head  700  near the sole portion instead of the bottom side of the golf club head  700 . In this alternative embodiment, instead of placing weight at specific locations, a plurality of weights  714 - 1 ,  714 - 2 ,  714 - 3 ,  714 - 4 , and  714 - 5  are all incorporated into the cavity  712 . In this embodiment, the central weight  714 - 1  may help retain the remaining weights  714 - 2 ,  714 - 3 ,  714 - 4 , and  714 - 5  in their respective locations when the desired weight configuration is achieved. In this embodiment, due to the fact that all  5  weights need to be present for the locking mechanism within the central weight  714 - 1  to work, different materials could be used for the plurality of weights. In an alternative embodiment of the present invention, the number of weights could deviate from the number articulated above to include more weights or even less weights, so long as the weights combine to fill out the entirety of the cavity. For example, the weights could be made out of different materials such as tungsten, steel, aluminum, plastic, rubber, or any other type of material that can be used to achieve a center of gravity change all without departing from the scope and content of the present invention. Finally,  FIG. 7  also shows that this current embodiment of the present invention may have a weight pad  710  located near a high toe portion of the back of the golf club head  700  to further adjust the center of gravity of the golf club head  700 . 
         [0041]      FIG. 8  of the accompanying drawings shows an exploded perspective view of a golf club head  800  in accordance with the further alternative embodiment of the present invention as shown in  FIG. 7 . The exploded view of the golf club head  800  shown in  FIG. 8  not only allows the relationship between the multiple weights  814 - 1 ,  814 - 2 ,  814 - 3 ,  814 - 4 , and  814 - 5  to be shown more clearly, but it also allows the cavity  812  to be shown. A closer examination of the cavity  812  will show that the cavity  812  in addition to providing a perimeter that conforms to the geometry of the plurality of weights  814 - 1 ,  814 - 2 ,  814 - 3 ,  814 - 4 , and  814 - 5 , also provides additional recess  813  within the cavity  812  to further remove weight from the muscle portion of the golf club head  800 . Removing weight from the muscle portion of the golf club head  800  may be desirable because it could create more discretionary mass. The discretionary mass created by the recess  813  within the cavity  812  can then be shifted to the plurality of weights  814 - 1 ,  814 - 2 ,  814 - 3 ,  814 - 4 , and  814 - 5  to further adjust the center of gravity of the golf club head  800 . 
         [0042]      FIG. 9  of the accompanying drawings shows a perspective view of a golf club head  900  in accordance with a further alternative embodiment of the present invention. The golf club head  900  may have an adjustable weight member  914  that can be placed at a plurality of different locations along a horizontal guide  934  using screws that engage the screw hole  930  on the weight as well as the screw holes  932  on the guide  934 . In this current embodiment shown in  FIG. 9 , the weight member  914  may be placed towards a heel portion of the golf club head  900  to promote a more heel biased center of gravity location. 
         [0043]      FIG. 10  of the accompanying drawings shows a perspective view of a golf club head  1000  in accordance with a further alternative embodiment of the present invention. In this embodiment of the present invention, the golf club head  1000  may have the adjustable weight member  1014  placed towards the toe portion of the golf club head  1000 , promoting a more toe biased center of gravity location. 
         [0044]    Finally,  FIG. 11  of the accompanying drawings shows a perspective view of a golf club head  1100  in accordance with a further alternative embodiment of the present invention. In this embodiment of the present invention, the golf club head  1100  may have the adjustable weight member  1114  placed towards a centralized location along the guide  1134 , promoting a more neutral and centered center of gravity location. 
         [0045]    Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification 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 above 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. 
         [0046]    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 from 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. 
         [0047]    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.