US20060172827A1

US20060172827A1 - String dampered with variable weight & balance racket sports

Info

Publication number: US20060172827A1
Application number: US11/341,378
Authority: US
Inventors: Frans Soekahar
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-01-28
Filing date: 2006-01-30
Publication date: 2006-08-03

Abstract

Lightweight and extremely stiff racket sports having four cushions with extended sleevings (21, 25, 26) which are located on the four sides of the racket frame string bed at 3, 6, 9 and 12 o'clock positions to isolate and dampen the shock and vibration during and after ball impact to reduce the possibility of arm injury and maximizing power energy transferred to the ball. String protectors (22, 25, 27) preventing the string to cut through the cushion sleevings. To enable every two facing cushions to have similar characteristics, a tunneling throat (28) is employed on the racket throat. A series of Tip weights (33) are located on the racket tip to make this lightweight racket becoming playable. These tip weights are then counter weighted by grip counterweight (31). Combinations of tip weights and grip weights will change the racket total weight and balance to suit individual players needs.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional patent application Ser. No. 60/647,447, filed Jan. 28, 2005 by the present inventor.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of Invention
This invention relates generally to sports rackets. The preferred embodiment is described in relation to a tennis racket but the invention principles may be applied to other types of sports rackets including squash racquets, badminton rackets, and racket ball rackets.
2. Prior Art
Racket flex is a rackets' characteristic that will make the racket feels soft and playable. Flex will also reduce possibility of arm injury. On the other hand this flex will also cause unpredictable ball bounce direction. Reducing or eliminating the racket flex will increase the racket power as well as possibility of arm injury. These phenomenons have been recognized before and many solutions have been suggested in various inventions/patents.
Basically, these solutions fall into one of two categories.
(1) Devices those are disposed between adjacent strings to dampen vibration;
(2) Modifying the frame, grommet strip including adding various shapes of inserts.
Robaldo U.S. Pat. No. 4,589,662 (1986) inserts a body of resilient material between the cords and Boschian U.S. Pat. No. 4,761,007 (1988) uses similar mechanism with different devices are two examples of the first type (113). Davis U.S. Pat. No. 4,828,259 (1989) modified the racket throat design by spaced the bridge portion apart longitudinally to enable a piece of vibration absorbing material is positioned between the upper and lower bridge section (112). Deville et al. U.S. Pat. No. 4,993,711 (1991) absorbs the vibration by placing an elastomer or soft rubber pliable annular member in the string sleeving interior are the examples of the second type (113). These devices dampen vibration in limited number of strings only, and do not absorb the shock. Shaw U.S. Pat. No. 5,762,570 (1998) suggests string protecting jackets tubular in shape made of rubber material as vibration damper. This type of damper will much too expensive to produce (114).
Second fact about the need of specific racket to a specific player is the racket weight and balance. There are three types of tennis players. A defensive players who plays mostly from base line, are also called a baseliner. The other extreme is an aggressive player who always tries to hit a net, is also called a serve-volleyer. The third player type is those who play both styles and called all-courter.
Each of this playing type needs different racket weight and balance to play. A serve-volleyer prefers a racket with head light where the racket center of gravity slightly closer to the grip for agility to move in the net. All-courters will prefer a center balance racket to fulfill their need on the baseline as well as on the net. A baseliner prefers to have a head heavy racket, a racket with center of gravity slightly closer to the racket tip so when it is swung, it generates higher kinetic energy.
Kinetic energy is energy possessed by an object, resulting from the motion of that object. The said energy is formulated by E=½ m v², where m is the mass of the object and v is the speed of the object. Thus reducing the object weight will increase the swing speed (bear in mind the same swing power is applied). While increasing swing speed will increase the energy exponentially, as of increasing the object's mass will increase the energy just arithmetically.
On the variable weight and balance also numerous attempts have been suggested such as Hufenus U.S. Pat. No. 4,427,195 (1984) and Kelmanski U.S. Pat. No. 4,179,121 (1979) by employing a movable weight along the shaft frame (115). Another method suggested by Chen U.S. Pat. No. 5,054,780 (1991) by adopting steel counter weights attached to the racket frame in string bed portion. These inventions are shifting the balance only. These inventions change the racket balance only and but will not affect neither racket weight nor racket power.
The Proposals Heretofore Carry a Number of Disadvantages:
(a) On the Shock absorber and Vibration damper none of the prior arts work simultaneously. Secondly the absorber and the damper applied to few center strings only. While employing dual material string grommet will increase the cost due to production difficulty.
(a) On the weight balance adjustments, the prior arts change the balance without capable to change the weight. While according to the ITF ruling, it is illegal to change racket weight or racket balance during the play.

BACKGROUND OF INVENTION—OBJECTS AND ADVANTAGES

Our method in shock absorption is isolating/cushioning the string from the racket frame with a high resilient vibration absorbing materials. The isolators/cushions are extended into the string bed area with plurality sleeving in the center of string bed for vibration damper. So during ball impact the string shock is absorbed/cushioned from the frame and then the following vibration is dampened by the plurality of the sleeving parts. The different length of the sleeving which is longest in the middle give most dampening effect in the center strings and in overall they will give better aesthetic look of the string bed. The current invention is also applicable to various shape and size of racket sports. With the suggested invention, most of ball impact will take place on the isolated strings.
Our method in weight and balance is distributing the weights on the racket edges. The racket itself should be light weight, adding the weight-balance will make the racket be playable as any ordinary racket. Started from the tip weights, these weights are then being balanced by grip (counter) weight. The total number of weights placed on the racket will determine the racket total weight, while the proportion of tip and grip will shift the racket balance. So the racket weight as well as balance can be adjusted to specific need. If these inventions are applied into an extremely stiff racket frame they will produce a powerful with high agility racket customizable according to specific users' requirements in weight & balance as well as minimizing the possibility of arm injury.

SUMMARY

These inventions improve shock absorbing, vibration dampening as well as adjusting variable weight & balance of a racket becoming possible. A cushion is made of high resilient vibration absorbing material cushions the string from the racket frame. These cushions will absorb the ball shock impact and prevent the following vibration being transferred to the frame. The said cushions have extended plurality sleeving to dampen the string vibration after impact. The lengths of sleevings are varied and their ends form a straight line in the string bed. These length differences will give most dampening effect in the center of the string bed. The plurality sleeving on all four string bed sides will dampen most ball impact as most strings are sleeved.
The tip and grip weights allow the user to adjust the racket weight and balance according to user's needs. The unique placement of tip weights will also increase the racket power and stability as well as extending the sweet spot upward. The tip weight will increase racket power when the racket is swung towards the incoming ball just like a sling is swung with a stone in it. Hurling the sling with a stone/weight on its edge generates centrifugal force that will tighten the sling and gives forwards acceleration on to the stone/weight. The grip counter weight make the racket feel light in hand and set the racket center gravity to where it is required.
Still further objects and advantages will become apparent from a study of the following description and the accompanying drawings.

DRAWINGS—FIGURES

FIG. 1 Prior arts.
FIG. 2 The perspective drawing of the invention.
FIG. 3 Exploded diagram of the invention.
FIG. 4 Frame cross section in the string area.
FIG. 5 Racket weight distribution and balance.
FIG. 6 Various shape of the sleeving.

DRAWINGS—REFERENCE NUMERALS

20 bumper guard
21 side cushion sleevings
22 side plastic protectors
23 string grommets
24 throat cushion sleeving
25 throat plastic protector
26 top cushion sleeving
27 top plastic protector
28 throat tunnels
29 string
30 racket frame
31 a stack of grip counter weights
32 but cap/counter weight retainer
33 pairs of tip weights
34 hollow string holes
35 string holes
36 conical cross section sleeving
37 hyperbolic cross section sleeving
38 cylindrical cross section sleeving
35 standard string holes
36 perimeter weight
37 trapezoidal cross section sleeving
38 hyperbolical cross section sleeving
39 cylindrical cross section sleeving

DETAILED DESCRIPTION

FIG. 1 is the prior arts. Diagram 111 shows a racket flexes and influences the ball bounce direction. Line A is ball incoming direction. N is perpendicular line to the string bed surface, N1 if the racket did not flex and N2 when the racket flexed. Line B is the ball bounce direction if the racket did not flex. a is the angle between incoming ball trajectory to normal; b is the angle between bouncing ball trajectory to normal in the case there is no flex. And c is the angle between incoming ball trajectory to normal; d is the angle between bouncing ball trajectory to normal in the case racket flexes. As a=b and c=d, bounce direction which supposed to be B due to racket flex now becoming C. The flex it self is depending on the racket stiffness and speed/power of the incoming ball hits the string bed. The faster the ball speed the more the racket flex will be while the stiffer the racket the less flex will be. The ball impact on to the string bed will produce shock and followed by string vibration. This shock and vibration cause arm injury especially on stiff racket (less flex racket). Diagram 112 is the prior art of variable weight racket and diagram 113 are prior arts of the frame/cushion modification vibration dampers. 114 is string protecting jackets tubular in shape made of rubber material as vibration damper and 115 is a movable weight along the shaft frame for balance adjustment.
FIG. 2 Perspective drawing of the rackets sport with the inventions.
FIG. 3 Exploded diagram of the invention that shows all components involved in the invention clearly can be seen the cushion sleevings (21, 24 & 26) and the throat tunneling design (28).
FIG. 4 Frame cross section in the string area.
FIG. 5 Racket weight distribution and balance. If a racket was sliced at 1 cm intervals along the length, then the weight of each sliced parts is shown in the weight distribution graph at the bottom page. The frame is made very light say 6-7 oz or less, then the tip weights (34) are added as required. These tip weights are then being balanced by grip counter weights (31) to maintain the center of gravity stay in the middle of the frame. Then all grip weights are tightened with the butt cap (32) to prevent another vibration. By adjusting number of the tip weights and grip counter weights, center gravity can be shifted along the frame as well as adjusting the racket total weight. Ideally a pair of tip weight weighs plus one grip counter balance are weighed about 1-2 oz. So at full weight balances in place, the overall racket weight will be about 11-12 oz. A cylindrical shape of lead with 3/16 inch diameter (5 mm dia.×50 mm) weighs about 0.257 oz (7.27 grams), a lead disc with 13/16 inch diameter, 3/16 inch thick (20×5 mm) weighs about 0.497 oz (14.07 grams). So total weigh per set of weight is about 1 oz.
FIG. 6 Various shape of the sleeving. Various possible shape of the sleeving such as cylindrical cross sections as shown in previous drawings. They are Trapezoidal cross sections (37), hyperbolical cross section (38) and cylindrical cross section (39) many other shape can also be adopted.

REFERENCE NUMERALS

20 bumper guard
21 side cushion sleevings
22 side plastic protectors
23 string grommets
24 throat cushion sleeving
25 throat plastic protector
26 top cushion sleeving
27 top plastic protector
28 throat tunnels
29 string
30 racket frame
31 a stack of grip counter weights
32 but cap/counter weight retainer
33 pairs of tip weights
34 hollow string holes
35 standard string holes
36 perimeter weight
37 trapezoidal cross section sleeving
38 hyperbolical cross section sleeving
39 cylindrical cross section sleeving

OPERATION

In operation, the very first step is deciding what racket weight a player would like to have and then go through following steps.
1. deduct required racket weight with the empty racket weight then divided the result by two and the weigh/number of tip and grip weights are found.
2. Place the tip weights in their locations start from top/center to the sides emphasizing more power that stability. To have a racket with more stability placed the tip weights from the sides to the top. Return the bumper guard on it place. And now the racket is ready for stringing.
3. Place the grip counter weight and close tightly the butt cap to avoid a new vibration generated, by adjusting the total grip counter weight, a correct balance is achieved. Adding/removing a pair of tip weight plus one grip disc will increase/decrease the racket weight but maintain the same racket balance.
4. String the racket as usual. The stringing process can be done before or after the step number 3.

Claims

1. A racket sports comprising:

(1) plurality high resilient materials string cushions and sleevings to eliminate/reduce shock and vibration during and after ball impact which are protected from string cut by rigid materials, to enable to have a top and bottom string bed symmetry, the throats have center opening slits to accommodate the throat cushion sleeping and throat protector,

(2) plurality of weight in pairs placed in its tip and grip mean to place the racket weight distribution on its ends and adjusting racket weight and balance.