Games using tangible projectile – Player held and powered – nonmechanical projector – per se,... – With sound-deadening – vibration-damping – or shock-absorbing...
Reexamination Certificate
2001-09-21
2003-09-23
Chiu, Raleigh W. (Department: 3711)
Games using tangible projectile
Player held and powered, nonmechanical projector, per se,...
With sound-deadening, vibration-damping, or shock-absorbing...
C473S537000
Reexamination Certificate
active
06623384
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a dynamic damper and a dynamic damper-installed tennis racket for improving shock and vibration characteristic thereof which are generated when we hit a ball with the tennis racket.
DESCRIPTION OF THE RELATED ART
The dynamic damper (vibration-damping member) having a viscoelastic part and a mass-adding part connected to the viscoelastic part is often used to reduce and relieve shock and vibrations generated in sports ball-hitting goods and tools when they are used. In the tennis rackets disclosed in Japanese Patent Publication No.52-13455 and Japanese Patent Application Laid-Open Nos.52-156031 and 4-263876, the cantilevered dynamic damper having a load-applying material fixed thereto through the elastic material is installed on the tennis racket. The dynamic damper resonates with vibrations of the racket frame to damp its vibration.
More specifically, in Japanese Patent Publication No.52-13455, as shown in
FIG. 23
, the cantilevered damper
6
consisting of the long and narrow elastic material is installed at the end of the grip
5
. The base of the steel wire
6
b
having a weight
6
a
installed on its front end is embedded in the racket frame. In Japanese Patent Application Laid-Open No.52-156031, as shown in
FIG. 24
, the base
3
a
of the dynamic damper is fixed to the throat
4
of the tennis racket, and the body
3
c
of the dynamic damper is connected to the base
3
a
via the neck
3
b
to vibrate the body
3
. In Japanese Patent Application Laid-Open No.4-263876, as shown in
FIG. 25
, the load-applying member
4
b
is fixed to the grip end
5
a
of the tennis racket via the elastic member
4
a.
In the above-described proposed conventional tennis rackets, to mainly suppress the 1st vibration of the racket frame in the out-of-plane direction (direction perpendicular to the gut plane of the racket frame), the configuration of the dynamic damper and the fixing position thereof are designed. That is, the load-applying material is fixed to the front end of one elastic material whose one end is fixed to the racket frame. The dynamic damper vibrates at the same frequency as that of the racket frame, thus consuming energy and reducing and damping the vibration and shock of the racket frame rapidly.
However, a player feels not only the vibration of the tennis racket in the out-of-plane direction but also the vibration thereof in the in-plane direction (widthwise direction of the racket frame parallel with the face of the racket frame). When the player hits a ball with at a position apart from the axis of the racket frame, the player feels a shock generated by the rotation of the grip very unpleasant.
The vibration in the in-plane direction has not been considered much. The vibration of the gut-stretched part in the in-plane direction is generated by deformation of the gut which hits the ball directly, thus giving a big influence on the player's evaluation on her/his ball-hitting feeling, namely, on whether the player feels good or bad when the player hits the ball with the tennis racket.
It is said that a so-called large racket having a large face area (area of gut-stretched part) developed to fly the ball a long distance generates more unpleasant vibration than a tennis racket having a small face area. This is because the large racket is liable to flex in the in-plane direction owing to the large face area. That is, the vibration of the gut-stretched part in the in-plane direction is large. From these facts, in the tennis racket such as the large racket designed to fly the ball a long distance, it is important to reduce the vibration in the in-plane direction in addition to the vibration in the out-of-plane direction.
Therefore the present applicant proposed a sectionally U-shaped dynamic damper as disclosed in Japanese Patent Application Laid-Open No.10-340836. The dynamic damper having the configuration can favorably reduce the vibration of the gut-stretched part in the in-plane direction in addition to its vibration in the out-of-plane direction.
The sectionally U-shaped dynamic damper can increase the vibration-damping performance in the in-plane direction in addition to that in the out-of-plane direction. But there is a case in which the effect for damping the vibration of the racket frame in the out-of-plane direction is smaller than that for damping the vibration thereof in the in-plane direction. To improve the vibration-damping performance, the dynamic damper has a room for improvement.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described problems. Thus it is a first object of the present invention to provide a dynamic damper superior in relieving and reducing shock and vibrations.
It is a second object of the present invention to provide a dynamic damper-installed tennis racket reducing vibrations of the racket frame in the in-plane direction in addition to the out-of-plane direction and having a vibration damping factor of not less than 1% in the in-plane direction and in the out-of-plane direction to reduce burden on a player's arm and allow a player to have a favorable feeling when the player hits a ball with the tennis racket.
To achieve the object, according to the present invention, there is provided a dynamic damper which comprises a viscoelastic part and a mass-adding part integrally layered on the viscoelastic part and is installed on a racket. The dynamic damper has a horizontal frame and a vertical frame disposed at both sides of the horizontal frame in the shape of a lattice. In the construction, the horizontal frame and the vertical frame are integrally formed or formed by joining the horizontal frame and the vertical frame separate from each other, the horizontal frame is installed on at least one surface of the racket in a thickness direction thereof, and the vertical frame is installed on both surfaces of the racket in a widthwise direction thereof.
The thickness direction of the racket means the direction perpendicular to the gut-stretched surface thereof. The widthwise direction of the racket means the direction parallel to the gut-stretched surface.
The horizontal frame is bent in the shape of a letter “U”. One end of a bent portion disposed at both sides of the horizontal frame is integral with the vertical frame or joined therewith. The bent portion disposed at both sides of the horizontal frame is installed on both surfaces of the racket in its widthwise direction.
It is preferable that the number of the horizontal frames is not less than two and that the horizontal frames are disposed, with the horizontal frames sandwiching a gut insertion hole therebetween. Thus in the case where the dynamic damper has two horizontal frames, it is rectangular. In the case where the dynamic damper has three horizontal frames, it has the shape of a Japanese character “
”. In the case where the dynamic damper has four horizontal frames, it has the shape of a Japanese character “
”.
That is, the lattice-shaped dynamic damper of the present invention has the long and narrow vertical frame integral with the horizontal frame or separate vertical frame and horizontal frame are jointed with each other.
As described above, the horizontal frame and the vertical frame are continuous and integral with each other and disposed in the shape of a lattice. Therefore in the dynamic damper-installed racket, the vertical frame resonates mainly with vibrations of the racket frame in a out-of-plane direction, whereas the horizontal frame resonates mainly with vibrations of the racket frame in a in-plane direction, thus effectively reducing vibrations in the out-of-plane direction and the in-plane direction. That is, because the horizontal frame and the vertical frame are disposed in the shape of a lattice, the dynamic damper has improved vibration-damping performance, thus reducing of shock and vibrations.
In the case where the dynamic damper is formed monolithically in the shape of a lattice, i.e., in the case where the vertical frame and the horizontal frame are formed in
Chiu Raleigh W.
Sumitomo Rubber Industries Ltd.
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