U.S. patent application number 10/162959 was filed with the patent office on 2003-02-20 for impact point development for golf clubs.
Invention is credited to Grim, Earl.
Application Number | 20030036440 10/162959 |
Document ID | / |
Family ID | 26859197 |
Filed Date | 2003-02-20 |
United States Patent
Application |
20030036440 |
Kind Code |
A1 |
Grim, Earl |
February 20, 2003 |
Impact point development for golf clubs
Abstract
A golf club with a gripping section at one end and a club head
having a heel portion and a toe portion, attached to the shaft at
the other end wherein said shaft centerline and a plane parallel to
the ground and tangent to said heel form a lie angle when said club
head is at rest and positioned to strike said golf ball; a club
head whose mass distribution is concentrated at said toe and heel;
a club face on said club head operable for striking a golf ball and
spanning the area between said heel and said toe of said club head
and having a heel to toe and sole to the top of club head bulge
defined by a radius whose center is offset toward said heel and
whose arc is swept from heel to toe of said club face; a lie angle
configured to maintain the impact point of said golf ball on said
club face when said impact point is off the center of mass.
Inventors: |
Grim, Earl; (US) |
Correspondence
Address: |
Eugene E. Renz, Jr., P.C.
205 North Monroe Street
Post Office Box 2056
Media
PA
19063-9056
US
|
Family ID: |
26859197 |
Appl. No.: |
10/162959 |
Filed: |
June 5, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60295882 |
Jun 5, 2001 |
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Current U.S.
Class: |
473/314 ;
473/324 |
Current CPC
Class: |
A63B 53/0433 20200801;
A63B 53/0466 20130101; A63B 53/02 20130101; A63B 53/0408 20200801;
A63B 60/00 20151001; A63B 53/047 20130101; A63B 53/04 20130101 |
Class at
Publication: |
473/314 ;
473/324 |
International
Class: |
A63B 053/04; A63B
053/02 |
Claims
What is claimed is:
1. A golf club with a gripping section at one end and a club head
having a heel portion and a toe portion, attached to the shaft at
the other end wherein said shaft centerline and a plane parallel to
the ground and tangent to said heel form a lie angle when said club
head is at rest and positioned to strike said golf ball; a club
head whose mass distribution is concentrated at said toe and heel;
a club face on said club head operable for striking a golf ball and
spanning the area between said heel and said toe of said club head
and having a heel to toe and sole to the top of club head bulge
defined by a radius whose center is offset toward said heel and
whose arc is swept from heel to toe of said club face; a lie angle
configured to maintain the impact point of said golf ball on said
club face when said impact point is off the center of mass.
2. A golf club as claimed in claim 1 wherein the lie angle which is
the angle between the centerline of the shaft and a horizontal
plane tangent to the sole of the club is greater than about
60.degree..
3. A golf club as claimed in claim 2 wherein the length of the
shaft measured from the connecting point to the head and the butt
end is between about 39' and 48'.
4. A golf club as claimed in claim 2 wherein height of the face of
the club measured from the tope edge to the sole edge at its
greatest point is about 1.732 inches.
5. A golf club as claimed in claim 1 wherein the distance from the
center of the face to the top edge is a about 0.984 inches for
titanium.
6. A golf club as claimed in claim 1 wherein the face is tilted
upwardly at an angle of about 5.degree..
7. A golf club as claimed in claim 1 wherein an angle made by club
face to the horizontal plane tangent to the sole of the head is
about 5.degree..
8. A golf club as claimed in claim 1 wherein the mass of the club
head is concentrated in predetermined area and combined with said
preferred lie angle provides an elliptical zone on the face of the
club whose major axis is generally perpendicular to the shaft and
wherein hits in the zone produce generally the same distance as
hits at the center of impact.
9. A golf club as claimed in claim 1 wherein the mass concentration
is higher in the toe and lower in the heel to maximize the moment
of inertia about the axis extending perpendicular to the diagonal
passing through the center of the face.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to the design of golf clubs
and in particular to the design of the driver, fairway woods, and
utility woods.
[0003] 2. Description of Related Art
[0004] The new technology advances in head design and especially in
shaft design have made possible the fabrication of longer lighter
clubs, especially in the woods. This has been used to market clubs
that are claimed to hit the ball further and be easier to use
because of their longer length and lighter shaft weight. However,
in general, the lengthening of the shafts of the club have made it
harder to hit the ball consistently in the center of the face, and
therefore has decreased the distance achievable with these new
clubs, rather than improving these characteristics.
[0005] Data published in the Golfsmith Technical Journal in Feb
1998 on the variation of the impact point of the ball on the club
face as a function of shaft length shows a consistent and
predictable pattern. It is a pattern that is also observed in the
wear patterns on the faces of drivers and irons used by the golfing
public. This pattern can be bounded by an ellipse, with the
elongated axis being perpendicular to the golfer's swing plane. The
major axis of this ellipse is about 2 inches in length, and the
minor axis is about 1.1 inches in length. The impact point pattern
found for a 45 inch driver at Golfsmith is shown in FIG. 1. With
the standard lie angles for the woods, as the club shaft length
increases the centerline of the impact ellipse moves off the top of
the club face, leading to fat, skyed shots.
[0006] Since the standard lie angle for golf clubs has been
established from experience, it is observed in the designs of the
major club makers. This angle is the angle subtended by a line
drawn down the centerline of the shaft, and a horizontal line which
is tangent to the sole of the club at the contact point that rests
on the ground at address. The standard lie for a driver is 54 to 55
degrees. However, it has been found by analysis that this lie angle
combined with even standard length woods does not fit the general
population. For the majority of the population the butt height of
the club lies in the range of 30 to 33 inches.
[0007] For shorter players and women it can go as low as 28 or 29
inches. An analyses show that the actual setup angles for driver
lengths of 42 to 46 inches range is from 40 to about 50 degrees.
This is compared to the lie angles provided by the manufacturers,
which range from 54 to 56 degrees. The reason for this difference
can be deduced from performance; even with these lie angles the
impact point of the ball is still moving off the top of the club
face. It would be worse with the lower lie angles, so that 54 to 56
degree lie angle approach was adopted by designers many years
ago.
[0008] The following photo demonstrates the optimum setup
parameters for the hands and the club position. This is
demonstrated by a picture taken in the GE laboratory in 1932, and
is still viable today. Jim Reynolds personified the modem ideal
setup and hand position to the ball even though this photo was
taken 70 years ago. His arms are vertical and his hands are low and
set up to the ball with a 45 degree shaft angle, shown by the white
lines.
[0009] His right hand is aligned along the shaft so that he
transfers power to the ball along the line to the target, and his
left hand is firm and angled up so that he overcomes the effects of
gravity, and keeps the club aligned on the ball.
[0010] The swing plane defined by the dotted line from the ball to
his shoulder is 60 plus degrees, which is consistent with the face
impact data that has been gathered from other sources.
[0011] This shows the typical setup parameters of 45 degrees for
the driver setup angle, and 60 plus degrees for the swing plane
angle.
[0012] The swing plane angle of 60 plus degrees influences the
diagonal angle that defines the major axis of the miss ellipse
shown in FIG. 1. The explanation of the motion of this miss area is
shown below. Descriptions of the behavior of the club during the
downswing of a number of professional golfers have been examined,
and the following conclusions have been reached:
[0013] As the club head is accelerated through the ball, there is a
very large increase in the head speed in a very small time
increment, as the hands release into the ball. This action and the
forces associated with it has been the focus of many training and
swing analyses. However, there is another force which tends to be
overlooked, and that is the force of gravity on the club head,
which operates continuously on the head, pulling it down towards
the ground.
[0014] Analysis of Charles Howell, an excellent young pro, shows
the relative timing of the segments of his downswing. These can be
correlated with the shaft deflection curves for other pros to
derive the predictions of the forces on the hands of the golfer
during the golf swing. At the time of the release of the hands
through the ball, Howell is 2/3 rds of the way down from the start
of the downswing to impact.
[0015] The majority of the acceleration through the downswing
occurs during the last third of his downswing, where the club
approaches the horizontal position that it has at impact. The time
for this increment of the downswing is about 0.15 seconds for
professional golfers. During this period, there is a torque on the
hands of about 15 ft-lbs. associated with the horizontal
acceleration of the club head into the ball, and a lesser, but
significant torque in the vertical plane due to the inexorable pull
of gravity on the club head equal to about 1 ft-lb.
[0016] If this is uncompensated the club head would drop about 7 or
8 inches during this short time. Even if the gravity pull is 90%
compensated by the golfer, the club head would drop about 0.78
inches, and this motion is normal to the swing plane. So the impact
point of the ball moves diagonally up and towards the toe about 0.8
inches if the gravity force is not compensated. It is noted that
the increase in torque (closely correlated with swing weight) on
the golfer's hands is about 7% for an increase of 3 inches in the
shaft length of the driver from the standard of 43 inches to 46
inches. If this is uncompensated by the golfer, as discussed above,
this will result in the motion of the impact point on the face up
and towards the toe by about 0.7 to 0.8 inches. The effect of the
gravitational pull on the head is shown in the following
diagram:
FIG. 3. SHOWS THE FORCES ON THE CLUB HEAD LINKED TO THE SWING PLANE
ANGLE
[0017] The gravity force component, if uncompensated will cause the
head to move downward and inward towards the golfer, which causes
the ball impact point to move from the center of the face to a
point diagonally upward towards the toe of the club. The other
gravity component, which is parallel to the swing plane, exerts a
pull on the hands which is compensated by a firm grip on the
club.
Discussion of the face dimension design for the new club
concept
[0018] The diagram below shows the relationship of the club design
parameters to the location of the miss ellipse on the face of the
club. The miss ellipse, from the above test data, is approximated
by an ellipse with a major axis dimension of 2 inches, and a minor
axis dimension of about 1.1 inches. The ball impact circle
diameter, caused by the compression of the ball at impact, has been
estimated from 0.7 inch to as much as 0.92 inches for the stronger
hitters now on tour.
[0019] Using the larger ball impact diameter figure, it can be seen
that the miss ellipse impact area is formed by the overlay of
multiple ball impact areas, showing that the locus of the center of
these ball impact areas is close to a line perpendicular to the
swing plane angle. For the larger ball impact circle diameter of
0.92 inches, the length of this perpendicular line is 1.08 inches,
i.e.; 2-.0.92 inches.
[0020] FIG. 4. The miss ellipse is linked to the swing plane angle,
and its long axis is perpendicular to this plane as seen in the
test data. Thus for an average golfer, if a mean swing plane angle
is 60 degrees, and his setup shaft angle is 45 degrees, with a
standard 55 degree lie angle, the impact ellipse is tilted up at 20
degrees to the horizontal axis of the face Using trigonometry, it
can be seen that the height of the impact ellipse at the toe would
be 0.83 inches, or 21 mm above the center of the face. On a
standard driver face, this would put the top of the miss ellipse
near or off the top of the face.
[0021] Alternatively, if a new driver design configuration is used,
with a lie angle of 61 or 62 degrees, and a face tilt up towards
the toe of 5 degrees, with the same swing plane angle and shaft
setup angle, the centerline of the face will be aligned within 9
degrees of the miss ellipse centerline. This will lower the top
edge of the miss ellipse by 10 mm, and bring the expected impact
points for the ball much closer to the sweet spot in this new
design.
[0022] The face height of a stainless steel driver is limited to
about 44 mm, or 1.732 inches, because of the limited volume of the
head designs. The new design concept will keep the generic miss
ellipse ball impacts well within the optimum hitting area, even on
the face of a generic stainless steel driver. Analysis of a
titanium head yields even better results. For a typical face height
of 50 mm for a titanium head design, the center to face top height
would be 0.984 inches, which would provide even a greater margin to
keep all ball impact circles on the face of the club. This new
design with a more upright lie and up-tilted face, will optimize
the performance of the club for center hits and for the most common
mis-hits towards the toe of the club.
[0023] A diagram showing these concepts is shown in FIG. 4.
[0024] An Autocad drawing is shown of a prototype driver head that
was fabricated in 1999, which embodied the new design concepts
described above.
[0025] FIG 5. The autocad drawing is shown above. The new driver
was fabricated in Dec 1999, and was successfully tested in Jan 2000
and April 2000. These tests were performed at the Impact Golf
Technologies facility in Ft Worth, Tex., using Iron Byron and the
instrumented test range at this facility. The test results were
very impressive, and showed that the center hits produced longer
drives than the control club, and was very superior in performance
for toe hits. Detailed plots of these results are shown in the
plots.
[0026] These tests were performed in April 2000 with Iron Byron
with a 95 mph head speed, and using a set of Strata balls. The
center hits were in the sweet spot of the face, the toe hits were
offset 0.5 in towards the toe, and 0.5 up from the centerline of
the face, and the heel shots 0.5 in towards the heel from the sweet
spot. Thus the toe hits were almost 3/4 inch offset, and the result
was only a 2 yard difference in range, and a 5 yard left offset.
This performance is considered to be excellent, and much better
than would result from a club with a standard lie. The heel
performance yielded a 10 yard range delta, and a 5 yard left
offset, also considered to be good performance.
[0027] FIG. 6. Tests with amateur golfers have also produced
excellent results, in terms of accuracy and distance compared to
the clubs they had been using. Result have been good for golfers
with handicaps from 8 to 25, and have been consistent and
repeatable. The 8 handicapper consistently hits this driver over
300 yards, with most of his hits in the fairway. Although he is a
naturally long hitter, none of the drivers he was using previously
compare with the results produced by this driver design, either in
distance or in accuracy.
* * * * *