PRIOR APPLICATION This is a continuation-in-part of application Ser. No. 10/334,643, filed Dec. 31, 2002, a continuation-in-part of Ser. No. 09/610,552, filed Jul. 5, 2000, a continuation-in-part of Ser. No. 09/407,031 filed Sep. 27, 1999, a continuation-in-part of Ser. No. 09/238,001 filed Jan. 26, 1999.
FIELD OF THE INVENTION This invention relates to the practice of the golf swing.
BACKGROUND OF THE INVENTION In the sport of golf, the ability to control the flight of the ball through striking it with a club is directly related to the quality and repeatability of one's golf swing. Because of the nature of the body, the design of the club and the flight characteristics of the ball the art of golf is complicated and the subject of endless discussion. To achieve consistent control over the golf ball, one must develop accuracy and consistency in the practice of their golf swing. Not only does this require significant practice, but also the knowledge of the proper fundamentals.
The training machines of the prior art, directed to the swinging of a golf club have attempted to create a physical motion reinforcement that develops the correct swing in the practicing individual. Unfortunately, no prior art has sufficiently accounted for the complexities and nuances of the golf swing and the golfer's anatomy to accomplish this. They have been lacking in the geometric theory and consequently in the physical construction. It is essential that a golf swing training device contain exactly the plurality and geometry of rotational axes and adjustments as does the present invention.
In order to provide the greatest training value, a practice machine should limit the motion of the swing to the correct motion while allowing the user to obtain the natural, free moving feel of its proper execution. It is also advantageous to provide adjustable and variable resistance during that motion to further enhance the training experience.
SUMMARY OF THE INVENTION The principal and secondary objects of this invention are to provide a training machine for the practice of golf in which a club or club simulating implement is propelled along a desired trajectory under forces applied by the arms and hands of the trainee; and to do so by constraining the movement of the hands and of the sporting implement to optimal trajectory planes and against adjustable resistance.
These and other valuable objects are achieved by a training device that is secured to a stationary frame at an adjustable height above ground and provides a structure for holding a golf club, or a golf club simulating device which is linked to the frame by an articulated assembly that keeps the hands of the user within an anatomically optimal plane regardless of the amount and direction of forces applied by the user. A plurality of rotational axes and unique geometry permit the body and club to behave in a manner consistent with the most desireable swing motion present in a natural golf swing.
Further, the apparatus may also comprise a laterally movable platform upon which the user stands while practicing the swing. The platform allows the user's feet or stance to move away from or toward the target of the practice swing. This motion allows the natural shifting of weight typical of a golf swing while preserving the circular motion of the hands relative to the core of the golfer's body. In practice of a real golf swing, the user's feet are typically anchored while the upper body of the golfer shifts away and toward the target. This feature of the present invention further increases the fidelity of the practice motion it provides to that of a real golf swing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of the first embodiment of the invention;
FIG. 2 is an isometric view of a golf club attachment assembly;
FIG. 3 is an isometric view of a golf club simulating attachment assembly;
FIG. 4a-b are isometric views showing rotation of a club rotating about axis D;
FIG. 5 is an isometric view of a hydraulic resistance mechanism;
FIG. 6 is a cross-sectional view of the linking portion of the resistance mechanism;
FIG. 7a is an isometric view of a model golfer in a backswing position;
FIG. 7b is an isometric view of a model golfer in a ball address position;
FIG. 7c is an isometric view of a model golfer in a finished swing position;
FIG. 8 is an isometric view from below the ground plane of a movable platform;
FIG. 9a-d are isometric views of a model golfer in a stationary frame of reference;
FIG. 10a-d are isometric views of a model golfer in a moving frame of reference;
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring now to the drawing, there is shown in FIG. 1, a motion training machine specifically adapted to the practice of golf which comprises a stationary frame in the form of a vertical column 1 which can be either mounted upon a ground surface or attached to a wall or ceiling. A frame member 2 projecting horizontally from a side of the column supports a first bearing housing 3 via a pivotal bracket 4. The bearing housing 3 is engaged by a first shaft 5 which is rotatable about a first oblique axis A. A receiving tube or sleeve 6 is attached, preferably, to the lower end of the shaft 5. A rotatable L-shaped arm 7 is slidably and axially engaged into the receiving tube 6. A second bearing housing 8 is secured to the distal end of the arm 7. A second shaft 9 is engaged into the second bearing housing 8. This shaft is rotatable about a second oblique axis B parallel to axis A.
Referring now to FIG. 2, a golf club assembly, slightly disassembled for clarity, comprises a first sleeve 10 connected by a first arcuate member 12 to a pair of coaxial sleeves 13. Axis B of the first sleeve 10 is perpendicular to axis C of the second pair of sleeves 13. A semi-circular member 14 is attached to two shafts 20 that are held coaxially in sleeves 13. A semi-circular member 15 is attached near its midpoint to the midpoint of the member 14. At one end of the semi-circular member 15 is attached a sleeve 16. Another sleeve 17 is attached to the opposite end of the member 15. A right-angle pivot pin 21 has a first portion attached to the inside top of the sleeve 16 such that the axis of the other portion of the pin which is perpendicular to the first portion is coaxial with the second sleeve 17. A golf club 18 is held by a retainer 23 mounted below the grip portion of the club. The retainer 23 has a hole bored along a third oblique axis D passing through the center of the mass 19, i.e., the axis of gravity of the golf club 18 which extends from a median portion of the club head to the center of its butt end. The remote portion of the pin 21 is engaged into the hole so that the retainer 23 and the club 18 can be rotated about axis D. A threaded insert 24 is fitted into the butt end of the club. A bolt 25 passes through the bearing housing 17 and engages the threaded insert, thus retaining the club against centrifugal forces during swinging. The first sleeve 10 can be slidingly and adjusted along the shaft 9 and is locked by a pin 11. The club handle assembly is free to rotate about axis B. The lower portion of the assembly, principally composed of the club 18, members 14, 15 and their attached components can rotate freely about Axis C which is perpendicular to Axis B. Referring now to FIGS. 4a-b, the club 18 can rotate freely about its axis of gravity 19 which is coaxial with Axis D. Axis D is perpendicular to axis C and coplanar with axis B.
Referring back to FIG. 1, the height of the device is adjustable by the sliding connection of the frame member 2 on the vertical column 1. The inclination angle of the trajectory plane is adjustable at the pivotal bracket 4. The radius that axis B describes about axis A relates to the length of the user's arms, and is adjustable by the sliding connection of the arm 7 and receiving tube 6. The user places his hands symmetrically astride the intersection of axes B, C and D on the handle of the golf club. Rotational force applied by the user are transmitted to the arm member 7 without inducing adverse motion in the other axes. The height of the machine, the slant of, and the distance between the axes A and B are adjusted to match the physical characteristic of the user. A counterweight 20 is slidably, fixably attached to the receiving tube 6 such that it counter acts the weight of all components rotating about axis A such that the user is only aware of the weight of the golf club.
Referring now to FIG. 3, a golf club simulating assembly comprises a first sleeve 10 connected by a first arcuate member 12 to a pair of coaxial sleeves 13. Axis B of the first sleeve 10 is perpendicular to Axis C of the second pair of sleeves 13. A semi-circular member 26 is attached to two shafts 20 that are held coaxially in sleeves 13. At the midpoint of the member 26 is a bearing housing 27 mounted such that its central axis is perpendicular to axis C and in the same plane as axis B of the first sleeve 10. A shortened golf club shaft 28 is retained in the bearing housing 27. At one end is a standard golf club grip 29 and at its distal end is a golf club head simulating weight 30. The assembly composed of the shaft 28, grip 29 and weight 30 is axially symmetric and relatively shorter than a standard golf club. It is freely rotatable in the bearing housing 27. The device of FIG. 3 acts similarly to that in FIG. 2 and has the advantage of being more compact and simpler in construction.
FIG. 5 shows a mechanism for providing cyclic resistance to the progression of the implement along its imposed trajectory, and more specifically, to the rotation about axis A. A yoke member 33 is slidably and adjustably engaged into the vertical column 1 to provide height adjustment for the whole machine. A pivot axle 34 spanning the arms 33A, 33B of the yoke can be immobilized by tightening the clamping arm ends of the yoke. Lever 36 is fixedly engaged by the axle 34 about its median portion. The adjustment of the angular position of the lever in reference to the yoke fulfills the same function as the pivotal bracket 4 of the first described embodiment of the invention. The lever 36 mounts at one end an elongated bearing housing 37 and a bearing sleeve 38 at the opposite end. The axes A and F of the housing 37 and sleeve 38 respectively are parallel. Referring to FIG. 6, a cross-sectional view of the bearing housing 36, 37 shows a first shaft 35 engaged into the lower half of the bearing housing and retained by bearings 47. The first shaft 35 is attached to a receiving tube 6 in like manner as the shaft 5 is attached to a similar receiving tube 6 in FIG. 1. The rotating arm 7 attachments are the same as previously described. The shaft 35 has a splined end 35A. A second shaft 39 is coaxially engaged into the top half of the bearing housing 37 and is retained by a similar bearings 47. The lower end 39A of the shaft 39 is splined and the upper end is attached to a crank arm 40. A spline coupling 41 slidably connects the first and second shafts 35 and 39. A slip ring 42 is fitted around the coupling 41. Two actuator pins 43 passing through windows 37A in the housing, and attach to the slip ring 42. The windows are shaped to allow vertical travel of the actuator pins 43. Doing so, disconnects the shafts 35, 39 and allows them to be angularly oriented at various positions in relation to each other.
Referring back to FIG. 5, a shaft 52 is retained in the sleeve housing 38 and orthogonally mounts a cylindrical clamp 44. A double acting hydraulic cylinder 45 is retained in the clamp 44. The rod of the hydraulic cylinder 45 connects to a bearing sleeve 46. A shaft 49 engaged in sleeve 46 projects from the crank arm 40 at a specified distance from axis A. A flow control means 50, which comprises a check valve and needle valve connected in parallel, is fitted to one port of the hydraulic cylinder 45. A plumbing connection 51 is made between the flow control means 50 and the opposite port of the cylinder 45. This embodiment resists rotation of the arm 7 about axis A in a cyclic manner. The preferred medium in the hydraulic cylinder is non-compressible fluid because it does not provide any spring-like energy storage. Rotation of the arm 7 through one revolution will encounter one cycle of resistance where the needle valve portion of the flow control means 50 determines resistance, and one cycle of less resistance where the needle valve is bypassed through the check valve. This configuration allows a user to repeatedly encounter resistance in one direction of rotation and easily return to a starting point. By lifting the coupling 41 off the shaft 35 and rotating arm 7 a specified amount, then re-establishing the coupling, the location of the resistance cycle can be moved to various locations within the range of motion. The number of splines on the end of shaft 35 determines the number of resistance positions.
FIGS. 7a, 7b and 7c show a model golfer 56 in three relevant positions of the golf swing as they would appear using the present practice apparatus. In the diagrams of FIGS. 7a, 7b and 7c the arc 54 defines the plane of travel of the hands of the user 56. The geometry of this arc is defined by the inclination I which is determined and fixed by locking of the pivotal bracket 4. The radius R of the arc 54 followed by the gripped handle of the club is defined by the adjustment of the arm 7 in relation to its receiving tube 6. Axis A passes preferably between the shoulders of the user 56 and its height in relation to the ground plane 55 is determined by adjustment of the frame member 2 along the column 1. The arc 54 and hence the plane of travel of the hands is perpendicular to axis A.
The arc 53 defines the plane of travel of the golf club. It is a principle of physics that a tethered object such as the golf club 18, propelled about a fixed axis will tend to describe a circle and hence a single plane of motion. For this reason, the golf club axis of gravity 19 will tend to travel on this plane during a swing. FIG. 7b shows the address and ball impacting position of the model golfer. If the swing were initiated with the club and the golfer's arms held in such a way to form a single plane, then the arcs 53 and 54 would converge to form a single plane, containing the hands of the user and the golf club axis of gravity 19. This would negate the need for the structure and rotational capability about axis C shown in FIGS. 1, 2 and 3. In practice this is anatomically undesireable. While the wrists are capable of holding the club at an angle of 180 degrees with the arms, they perform more naturally with an angle less than 180 degrees. When a swing is initiated with this condition, the club and hands will travel on intersecting planes to adhere to the principles of physics mentioned above. Because of the exactness of axes B, C and D, the hands of the user can travel on the more inclined plane defined by arc 54 while allowing the complete range of anatomical function and allowing the golf club and its axis of gravity 19 to travel on a less inclined plane as defined by arc 53. Rotation about axis C permits the naturally changing relationship between the club shaft and the arms. At the address position, the angle between axis-D and axis B can be seen to be less than 90 degrees. At the ends of the swing seen in FIGS. 7a, 7c this angle can be seen to be greater than 90 degrees.
Referring to FIGS. 1 and 7a-c, the function of the four axes of rotation can be seen. Rotation about axis A is the gross movement of the swing. Rotation about axis B allows for the cocking of the wrists. This action typically will form a right angle between the club shaft and the arms at the two ends of the swing shown in FIGS. 7a, 7c.
Rotation about Axis D allows the rolling of the wrists through typically 180 degrees. At address and impact, the wrists are typically neutrally positioned. When the club is swung backwards, the wrists typically roll 90 degrees away from the target and when the club is swung forward, they typically roll 90 degrees forward. The rolling of the wrists translates directly to the changing angle of the club face. It can be seen in FIG. 7a that the club face has opened 90 degrees and is essentially coplanar with the club plane of travel. FIG. 7c shows the club face has closed 90 degrees and is essentially coplanar with the club plane of travel. This is done in concert with the wrist cocking motion described before. At the moment of impact, the club face must be square with the intended direction of travel to achieve a straight shot, so that the wrist roll and cock are principally 0 degrees, or centered in their range of travel. FIG. 7b shows that the club face is essentially perpendicular to the club plane of travel and square with the intended direction of ball travel. The wrists are un-cocked and centered in their range of rolling motion.
FIG. 8 shows a typical embodiment of a movable platform, as viewed from below the ground plane. A base frame 57 has a vertically oriented column 58 at one end for attachment of a frame member 2, such as shown in FIG. 1. At the ground level of the base frame 57, two linear shafts 59 are attached internally. Four linear bearings 60 are carried on the shafts 59 and attached to a movable platform 61. The movable platform 61 allows lateral movement of a user's feet and stance relative to the fixed column 58, allowing a variable relationship between the principle axis of rotation A and the user's stance.
FIGS. 9a-10d show a model golfer 56 standing on a movable platform 61, demonstrating a full swing as viewed through two frames of reference. In the figures, R designates the center of rotation of the golfer's swing. S and W are reference locations for the golfer's stance, or feet position and resulting weight. F designates a fixed line in the frame of reference. Axis A as shown in FIG. 1 extends into and out of the page and passes through R, the center of rotation of the golfer.
FIGS. 9a-d are viewed from a fixed frame of reference with the world, as someone would view the present invention being used. The arc 54, which is the arc of travel of the hands of the golfer, is circular because the golfer's center of rotation R is fixed in space. FIG. 9a shows the golfer at an address position, where their weight W, stance S and center of rotation R are aligned. As the golfer takes a backswing in FIG. 9b, the golfer's stance S moves forward with the movable platform 61 while their weight W stays in place. FIG. 9c shows the golfer moving their stance S backward in a transitional move. FIG. 9d shows the completion of the swing with the golfer's weight W forward of their stance S. From this frame of reference, the golfer's hands travel a circular arc 54, their weight W and center of rotation R stay fixed while their stance S shifts forward, then backward during their swing, accommodated by the moving platform 61.
FIGS. 10a-d are viewed from a moving frame of reference with the world, as someone would view the present invention, were they on the movable platform 61. The curve 62, which is the arc of travel of the hands of the golfer, is elliptical in nature because the golfer's center of rotation R will move laterally in the frame of reference while they perform a circular motion. It has hysteresis, because the golfer's swing, has different sequence of events in the backswing and forward swing. FIG. 10a shows the golfer at an address position, where their weight W, stance S and center of rotation R are aligned. As the golfer takes a backswing in FIG. 10b, the golfer's weight W and center of rotation R move backward. FIG. 10c shows the golfer moving his weight W and center of rotation R forward in a transitional move. FIG. 10d shows the completion of the swing with the golfer's weight W forward of their stance S. From this frame of reference, the golfer's hands travel the elliptical path 62 with hysterisis. Their weight W and center of rotation R move backward in the backswing, then shift forward for the forward swing.
This feature of the present invention, the laterally moving platform, allows the present invention to mechanically reinforce a preferred elliptical swing path which accommodates the natural shifting of a golfer's weight and center of rotation backward and forward. While doing so, the precise circular geometry of the features shown in FIG. 1 remains intact along with the behavior shown in FIGS. 7a-c, working to reinforce the most desirable swing mechanics. A user's feet move forward and backward during a practice swing while their center of rotation stays fixed in space. In a real golf swing, the golfer's feet stay stationary while their center of rotation shifts backward and forward. This is an inconsequential difference between the present invention and a real golf swing because the user must utilize all of the same muscles and techniques in the same manner to effect a swing with the present invention as they would with a golf club in a normal golf swing.
While the preferred embodiments of the invention have been described, modifications can be made and other embodiments may be devised without departing from the spirit of the invention and the scope of the appended claims.
