Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION
TRAINING BAT
[0001] (Intentionally blank)
FIELD OF THE INVENTION
[0002] The invention relates generally to sports training devices and
more particularly
in some embodiments to baseball/softball training bats designed to improve
swing timing
and mechanics.
DESCRIPTION OF THE RELATED ART
[0003] Training bats or clubs with either a cylindrical or spherical
stationary weight
are well known. Many a baseball training bat involves "donuts" or other
weights which are
used primarily to develop strength or practice and perfect the swinging
technique of the
hitter. Such structures have included bats having unusual weight distribution
as well as
bats having removable or movable weights supported therein or thereon.
[0004] For example, U.S. Pat. No. 514,420 disclosed a bat in which an
impact force
multiplying device is provided. The impact device includes an elongated hollow
passage
defined within the striking end of the bat within which a plurality of
weighted spherical
balls are freely movable. A closure plug is thrcadably received at the
striking end of the
bat closing the passage and captivating the weighted balls within the passage.
In an
alternate embodiment, an elongated cylindrical sliding weight replaces the
spherical balls.
The intended function is provided by the change of bat characteristic during
swinging as
centrifugal force drives the weighted members outwardly from the passage end
remote
from the striking end to the striking end of the bat.
[0005] Another example includes U.S. Pat. No. 3,578,801, which sets
forth a practice
bat having an elongated hollow bat for baseball practice within which an
elongated
longitudinal rod is supported. A chamber extends along a portion of the
elongated rod and
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supports a slidable weight thereon. During the swinging of the bat, the
centrifugal force
drives the weight outwardly toward the striking end of the bat.
[0006] While the foregoing devices are useful for their intended
purposes, there
remains a continuing need in the art for evermore improved practice devices
such as game
bats or the like.
SUMMARY OF THE INVENTION
[0007] The disclosure relates in general to practice device such as a
bat that has a
hollow body defining a interior volume extending within a barrel portion of
the bat. The
interior volume includes a slidable mass having a passage that extends through
the mass in
the direction of movement. Moreover, the slidable mass is contained within the
bat's
interior volume and may be in contact with an interior circumference of the
bat or inside a
sleeve within the bat, thereby slidably engaged along the bat's interior
circumference
during a swinging motion.
[0008] The slidable mass means a changing (dynamic) moment of inertia
(MOI).
Therefore, embodiments may include a passage in the mass that has a different
diameter at
each end or within the passage, thereby providing a way to control the rate of
change of the
inertia (i.e., a control mechanism for dynamic MOD.
[0009] The moment of inertia changes as the mass moves further from the
center of
rotation. The following relationships describe this effect:
[0010] I = moment of inertia = the moment of inertia of the bat (I bat) +
the product
of the mass of slider times the square of the distance (r2) from the center of
rotation. Thus,
I total = I bat + slider mass x r2 where r increases.
[0011] Various other purposes and advantages of the invention will
become clear from
its description in the specification that follows. Therefore, to the
accomplishment of the
objectives described above, this invention includes the features hereinafter
fully described
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in the detailed description of the preferred embodiments, and particularly
pointed out in the
claims. However, such description discloses only some of the various ways in
which the
invention may be practiced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 depicts a front perspective view of an embodiment of a
slidable mass
for the inventive bat.
[0013] Figure 2 depicts a back perspective view of the embodiment of a
slidable mass
for the inventive bat shown in Figure 1.
[0014] Figure 3 depicts a front elcvational view of the embodiment of
the slidable
mass shown in Figure 1.
[0015] Figure 4 depicts a back elevational view of the embodiment of the
slidable mass
shown in Figure 2.
[0016] Figure 5 depicts a side cicvational view of an embodiment of the
inventive bat.
[0017] Figure 6 depicts a cross-sectional view of the embodiment shown in
Figure 5
and taken along line A-A.
[0018] Figure 7 depicts an enlarged cross-sectional view of the slidable
mass in the
embodiment shown in Fig. 6 and taken along the section defined by circle B.
[0019] Figure 8 depicts an alternative embodiment of a slidable mass.
[0020] Figure 9 depicts a cross-sectional view of a bat utilizing the
slidable mass of
Fig. 8 and an accessory sleeve.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Referring to Figs. 1-4 and 6, a slidable mass 2 is shown having a
passage 4 that
extends through the mass in the direction of movement M. The slidable mass 2
is
generally cylindrical (although ovoid and other shapes are possible) and may
be made of
metal such as steel or aluminum depending on the amount of weight desired.
While not
shown in the drawings, it should be understood that more than one mass 2 may
be included
or that "stackable" or "nesting" masses may be used in lieu of a single
slidable mass,
thereby giving the ability for both customizing both the amount of weight and
the "feel" of
the bat. A coating or lubricant may be used on the mass 2 and/or inner surface
of the bat to
aid in sliding.
[0022] The mass 2 further includes an outer surface 6 that preferably
contains one or
more seal(s) 8 to provide a smooth sliding motion. For example, a pair of
seals disposed
around a circumference of the mass 2 proximal to each end of the mass may be
utilized. In
the finished training bat, the seal(s) 8 are in contact with an interior
circumference of the
bat as shown Figs. 6 and 7 and described in further detail below and may be
made of a
material allows for sliding movement, such as nylon or
polytetrafluoroethylene, against the
interior surface of the bat. While the seal(s) are shown to be anular in
structure, any other
configuration that allows sliding of the mass 2 while in contact with the
inner
circumference of the bat may be used.
[0023] The passage 4 that extends through the slidable mass 2 preferably
has a
different diameter at each end of the mass, for example, diameter 10 and
diameter 12 in
Figs. 3 and 4, respectively. The different diameter openings may extend a
predetermined
distance through the mass 2, as shown for example in Fig. 6, thereby causing
the passage
to have different diameters. By having different diameters for the passage,
the speed of
motion for the mass 2 is more precisely controllable, leading to different
effects during a
swing motion. For example, with the mass located close to the center of
rotation at the
start of a swing, the smaller inertia allows control and enhanced bat angular
acceleration.
Under a force due to centripetal acceleration, the mass slides outward. The
orifice
provides a method of controlling the rate at which the mass moves toward the
end of the
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bat, with the purpose of optimizing the location of the sweet spot (center of
percussion) at
the time of bat and ball impact, and as the mass moves further outboard,
providing
increased inertia which aids in the training of swing follow through.
5 [0024] Turning to Figs. 5-7, an embodiment of an inventive bat 20
utilizing the sliding
mass described above is shown. The bat includes a relatively thick barrel
portion 22
topped by an end cap 24, which may act as a stop for the mass 2 and thus be
made of
rubber or a similar material, a junction or handle taper portion 26, and a
handle portion 28.
Different bat styles may be used, with or without an end cap, depending on
desired
characteristics and ability to change or alter the slidable mass 2.
[0025] The slidable mass shown in this embodiment is free from contact
with any
structure within the barrel portion 22 except for the interior circumference
30 upon which
it slides and the end cap 24 (other embodiments may not have an end cap,
however, in
which case the mass contacts the end of the barrel portion 22). Hence, during
a bat user's
swing, the mass 2 will move M toward the bat end/end cap while air goes
through the
passage 4.
[0026] While not intending to limit this disclosure to any particular
mechanism of
action, the following explanation of the mechanics of the inventive bat is
provided. The
slidable mass 2 provides a dynamic Moment Of Inertia (MOI) with a reduced
initial MOI
prior to initiating a swing. In the action of swinging the bat, a centripetal
acceleration acts
on the bat causing a shift in position of the slidable mass, which increases
the MOI as the
swing progresses.
[0027] In other words, the reduced MOI at the beginning of the swing
allows the batter
to achieve a higher swing speed with more control up to the point of ball
contact. With the
increased MOI in the later part of the swing, the bat user is trained to
follow through the
swing after the ball/bat contact is completed.
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[0028] Moment of inertia is a physical property which provides a measure
of a body's
resistance to a change in its angular rotation velocity. The determination of
MOI is
accomplished by defining a group of small individual mass particles, the sum
of which
equals the total mass, and defining the distance (n) of the mass particles
(mi) from a
specified axis of rotation. The MOI can then be calculated as:
2
ip = E 711iTi .
i=1
Where N is the total number of discrete particles and subscript p is the point
through with the
axis of rotation passes
Thus, the inventive bat works by the movement of the mass due to centripetal
acceleration
toward a closed volume of air in the end of the bat. The action of the moving
slidable
mass compresses the air into a smaller volume with higher pressure, causing
the air to
flow through an passage through the center of the mass. The passage restricts
the flow
providing a control mechanism for the rate of slider movement, and hence the
change of
MOI. Consequently, the swing dynamics can be customized for the strength and
other
attributes of different hitters.
[0029] Figures 8 and 9 depict an alternative embodiment of a slidable
mass for use
inside a bat of the invention and an accessory sleeve. The generally
cylindrical sleeve 40,
which may be made of any rigid material such as metal but preferably is made
of resilient
material like urethane, can be added to the bat interior such that it is
nested within the
interior surface 30 of barrel portion 22. The sleeve provides an additional
channel in
which the slidable mass is contained such that any dents or other damage to
the barrel
portion 22 do not interfere with the sliding motion of the mass.
[0030] The sleeve 40 may include a hole 42 such that air may be released
form the
sleeve as a slideable mass 44 moves towards the hole. In this embodiment of
the slidable
mass, a passage 50 exists through the mass 44 to allow air transfer during
movement of the
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mass and a weight 46 is removably attached within threaded portion 48. The
weight 46 is
removable to facilitate the use of different weights according to the
preference of a user.
[0031] Figure 9 depicts a cross-sectional view of a bat utilizing a
sleeve and the
slidable mass of Fig. 8. Because of the tapered conical shape and length of
weight 46, it
protrudes into the taper portion 26 of the bat and may even reach the end of
the handle
portion 28, depending on the bat. Thus, a user experiences an improved swing
motion as
the slidable mass 44 and attached weight 46 travel almost the length of the
bat from the
handle to the end cap 24.
[0032] While the bat 20 and sleeve 40 can be designed such that the end
cap 24 and the
handle portion 28 stop the motion of the slidablc mass 44 such that it is
contained within
the sleeve 40, the sleeve may also include end fittings 52 (e.g. a plug) and
54 (e.g. a
grommet) that fit in an opening and around the circumference of the sleeve 40
such that the
slidable mass 44 is contained inside and the sleeve is positioned with a space
between the
sleeve and interior surface 30 of the bat. The end fittings may be additional
components or
may be formed with the sleeve to be of one-piece construction.
[0033] In addition, a kit is provided comprising a bat with a hollow
interior and
removable end cap, a cylindrical sleeve that fits in nested arrangement within
the hollow
interior, and a slidable mass configured to slide within the sleeve. An
assortment of
detachable weights, end fittings, and other accessories may further be
included.
[0034] Various changes in the details and components that have been
described may be
made by those skilled in the art within the principles and scope of the
invention herein
described in the specification and defined in the appended claims. Therefore,
while the
present invention has been shown and described herein in what is believed to
be the most
practical and preferred embodiments, it is recognized that departures can be
made
therefrom within the scope of the invention, which is not to be limited to the
details
disclosed herein but is to be accorded the full scope of the claims so as to
embrace any and
all equivalent processes and products.
