U.S. patent application number 13/471959 was filed with the patent office on 2012-12-20 for golf club head.
This patent application is currently assigned to BRIDGESTONE SPORTS CO., LTD. Invention is credited to Wataru BAN, Kozue WADA.
Application Number | 20120322578 13/471959 |
Document ID | / |
Family ID | 47354115 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120322578 |
Kind Code |
A1 |
BAN; Wataru ; et
al. |
December 20, 2012 |
GOLF CLUB HEAD
Abstract
This invention discloses a golf club head which has a hollow
shell structure and includes a face portion, a sole portion, a
crown portion, a back portion, a toe-side side portion, and a
heel-side side portion. A ratio R/H.times.100% is 5% to 20%, where
R is the radius of curvature of the upper corner edge on which the
face portion and the crown portion intersect with each other, and H
is the maximum head height.
Inventors: |
BAN; Wataru; (Chichibu-shi,
JP) ; WADA; Kozue; (Minato-ku, JP) |
Assignee: |
BRIDGESTONE SPORTS CO., LTD
Tokyo
JP
|
Family ID: |
47354115 |
Appl. No.: |
13/471959 |
Filed: |
May 15, 2012 |
Current U.S.
Class: |
473/345 |
Current CPC
Class: |
A63B 53/0466 20130101;
A63B 2225/01 20130101; A63B 53/04 20130101; A63B 53/0412 20200801;
A63B 60/00 20151001; A63B 53/0408 20200801 |
Class at
Publication: |
473/345 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2011 |
JP |
2011-132523 |
Claims
1. A golf club head which has a hollow shell structure and includes
a face portion, a sole portion, a crown portion, a back portion, a
toe-side side portion, and a heel-side side portion, wherein a
ratio R/H.times.100% is 5% to 20%, where R is a radius of curvature
of an upper corner edge on which the face portion and the crown
portion intersect with each other, and H is a maximum head
height.
2. The head according to claim 1, wherein the ratio is 10% to
15%.
3. The head according to claim 1, wherein in a longitudinal
sectional view taken along a line which runs in a front-to-back
direction and passes the face center, when a contact point between
the upper corner edge and a tangent to an outer surface of the
upper corner edge, which is inclined by 45.degree. backwards from a
vertical direction, is defined as A, a point on an upper edge of
the face portion is defined as B, and a point C which forms a line
segment AC having a length equal to a length of a line segment AB
is set on a side of the crown portion, the radius of curvature is
equal to a radius of curvature R of an arc which passes through the
points B, A, and C.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a hollow golf club
head.
[0003] 2. Description of the Related Art
[0004] Golf club heads which are made of a metal and have a hollow
shell structure are widely used as wood type golf club heads such
as a driver and a fairway wood type golf club head. In general, a
hollow wood type golf club head includes a face portion for hitting
a ball, a crown portion which forms the upper surface portion of
the golf club head, a sole portion which forms the bottom surface
portion of the golf club head, a side portion which forms the toe-
and heel-side side surface portions of the golf club head, a back
portion which forms the back surface portion, and a hosel portion
in which a shaft is mounted. A shaft is inserted into the hosel
portion and fixed by, for example, an adhesive. In recent years, a
variety of golf clubs called utility clubs (hybrid clubs) have also
become commercially available. As one type of utility golf club,
various golf clubs having heads similar to the above-mentioned wood
type golf club head (that is, heads each having a face portion,
sole portion, side portion, back portion, crown portion, and hosel
portion) are commercially available.
[0005] Although an aluminum alloy, stainless steel, or a titanium
alloy is typically used as a metal which forms the hollow golf club
head, a titanium alloy is especially widely used these days (for
example, Japanese Patent Laid-Open No. 2003-88601).
[0006] In general, as the volume of a hollow golf club head
increases, the air resistance of the head upon a swing also
increases.
[0007] Japanese Patent Publication No. 7-93956 describes a groove
formed in the crown portion to extend in the toe-to-heel direction
so as to reduce the air resistance of the head.
[0008] As described in Japanese Patent Publication No. 7-93956,
even if forming a groove in the crown portion produces an effect of
reducing the air resistance of the head, this may hinder the
flexure of the entire crown portion upon hitting a ball, thus
producing a negative effect in terms of increasing the flight
distance.
SUMMARY OF THE INVENTION
[0009] An objective of the present invention is to provide a golf
club head which can reduce air resistance without forming a groove
in the crown portion, and increase the flight distance.
[0010] According to the present invention, there is provided a golf
club head which has a hollow shell structure and includes a face
portion, a sole portion, a crown portion, a back portion, a
toe-side side portion, and a heel-side side portion, wherein a
ratio R/H.times.100% is 5% to 20%, where R is a radius of curvature
of an upper corner edge on which the face portion and the crown
portion intersect with each other, and H is a maximum head height.
Note that the maximum head height H is the distance between a
horizontal surface in contact with a lowest sole point and that in
contact with a highest crown point while the golf club head is
soled.
[0011] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a golf club head according
to an embodiment of the present invention;
[0013] FIG. 2 is a sectional view taken along a line II-II in FIG.
1;
[0014] FIG. 3 is a view for explaining the shape of the upper
corner edge of the golf club head shown in FIG. 1;
[0015] FIG. 4 is an aerodynamic force diagram of the golf club head
shown in FIG. 1; and
[0016] FIG. 5 is an aerodynamic force diagram of the conventional
golf club head.
DESCRIPTION OF THE EMBODIMENTS
[0017] A golf club head 1 according to an embodiment will be
described below with reference to FIGS. 1 to 4. Simply put, the
golf club head 1 has a given loft angle, so air flows from the face
portion to the crown portion in large amounts during a swing. For
this reason, the upper corner edge of the head, on which the crown
portion and the face portion intersect with each other, is rounded.
Therefore, air that collides against the head upon a swing smoothly
flows upwards, so the air resistance of the head upon a swing
reduces. This makes it possible to easily raise the head speed to
increase the flight distance. Also, in a driver head, a ball is
placed on the tee and struck, so the head passes through a line
higher in level than the ground surface by several centimeters. For
this reason, the lower corner edge of the head, on which the face
portion and the sole portion intersect with each other, is
preferably rounded more than the upper corner edge of the head, on
which the crown portion and the face portion intersect with each
other. Little air flows through this lower portion due to factors
associated with the loft angle. The sole portion is straighter
(than the crown portion), and is therefore less likely to peel
off.
[0018] The golf club head 1 uses a wood type golf club head (a
driver in this embodiment) which has a hollow shell structure and
includes a face portion 2, sole portion 3, back portion 4, crown
portion 5, toe-side side portion 6, heel-side side portion 7, and
hosel portion 8.
[0019] The face portion 2 forms a surface for hitting a ball, and
is provided with grooves (scorelines) (not shown). The sole portion
3 forms the bottom surface portion of the golf club head 1, and the
crown portion 5 forms the upper surface portion of the golf club
head 1.
[0020] The back portion 4 forms the back surface portion of the
golf club head 1. The toe-side side portion 6 and heel-side side
portion 7 connect the back portion 4 and face portion 2 to each
other. Also, the back portion 4, toe-side side portion 6, and
heel-side side portion 7 connect the sole portion 3 and crown
portion 5 to each other. A shaft (not shown) is inserted into the
hosel portion 8, and fixed by an adhesive.
[0021] Although the golf club head 1 is made of a metal in this
embodiment (titanium or a titanium alloy in this embodiment), at
least part of the crown portion 5 may be made of CFRP (Carbon Fiber
Reinforced Plastics). Note that a cone which has a specific gravity
of 8 or more and especially about 10 to 16, and is made of, for
example, copper, a copper-lead alloy, a tungsten alloy, or a
copper-lead-tungsten alloy may be provided in an appropriate
portion on the golf club head 1.
[0022] In this embodiment, the upper corner edge of the golf club
head 1, on which the face portion 2 and the crown portion 5
intersect with each other, is rounded more than that of the
conventional golf club head. More specifically, in longitudinal
sectional views (FIGS. 2 and 3) taken along a line which runs in
the front-to-back direction and passes through the face center
while the golf club head 1 is soled, when the contact point between
the upper corner edge and a tangent to the outer surface of the
upper corner edge, which is inclined by 45.degree. backwards from
the vertical direction, is defined as A, a point on the upper edge
of the face portion 2 is defined as B, and a point C which forms a
line segment AC having the same length as a line segment AB is set
on the side of the crown portion 5, the upper corner edge is
rounded so that a ratio R/H.times.100% is 5% to 20% and especially
10% to 15%, where R is the radius of curvature of an arc which
passes through the points B, A, and C, and H is the maximum head
height. In contrast to this, the conventional titanium driver head
has a ratio R/H.times.100%=about 2% to 4%.
[0023] Note that the upper edge of the face portion 2 is defined as
a point at which the radius of curvature of a face surface formed
by a surface that is approximately flat but is slightly convexly
curved starts to increase in the longitudinal sectional view shown
in FIG. 3. That is, referring to FIG. 3, the radius of curvature of
the face surface is constant on the side below the point B, but is
larger on the side above the point B than on the side below the
point B.
[0024] In a golf club head having an upper corner edge rounded more
than the conventional golf club head in this manner, air that
collides against the head upon a swing smoothly flows upwards, so
the air resistance of the head upon a swing is low. FIG. 4 is an
aerodynamic force diagram showing the flow of air from the upper
corner edge to the vicinity of the crown portion when a wind tunnel
test is conducted for a golf club head 1 having a ratio R/H
(maximum head height).times.100%=12%. FIG. 5 is an aerodynamic
force diagram of the conventional golf club head which has a ratio
R/H (maximum head height).times.100%=3% and an angled upper corner
edge. In the conventional golf club head, the laminar flow of air
separates from the crown portion on the upper corner edge, so the
air resistance of the head is high, as shown in FIG. 5. In contrast
to this, in the golf club head shown in FIG. 4, which has a rounded
upper corner edge, the laminar flow of air along the crown portion
reaches the rear portion of the crown portion, so the air
resistance of the head is low.
[0025] Note that the lower corner edge on which the face portion
and the sole portion intersect with each other, and the heel- and
toe-side corner edges on which the face portion and the heel- and
toe-side side portions intersect with each other may be rounded as
well. The present invention is preferably applicable to a driver
head having a volume of 400 cc or more and, for example, 430 to 460
cc.
Example
[0026] A golf club (driver) was manufactured by mounting a carbon
shaft in a titanium driver head (Example) having a volume of 460 cc
and a ratio R/H.times.100%=12% so that the club length was 45
inches. The average of the head speeds at which this driver was
swung five times was 39.7 m/sec.
[0027] The head speed of a driver on which a driver head
(Comparative Example) having the same specifications as the driver
head according to the Example except for having a ratio
R/H.times.100%=3% was mounted was measured in the same way as above
and found to be 39.4 m/sec.
[0028] The above-mentioned result verifies that the head speed
increases when the upper corner edge is rounded more.
[0029] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0030] This application claims the benefit of Japanese Patent
Application No. 2011-132523, filed Jun. 14, 2011, which is hereby
incorporated by reference herein in its entirety.
* * * * *