JPH0568562U - Vibration absorber for sports rackets - Google Patents

Abstract

(57) [Summary] [Object] To provide a vibration damping device that gives variable vibration damping characteristics to the entire area of a string surface. In particular, a large damping is applied to the outer longitudinal string, and a small vibration damping is applied to the central longitudinal string. Therefore, when the ball hits the outside of the racket, it gives great braking, but when the ball hits the center of the stringing area, it gives small braking, so the string stays elastic and keeps bouncing well. You can The vibration damper (10) comprises a relatively thin, flexible elastomeric strip (12) having a pair of large mass end sections (14). Each end section is a string (34)
Groove (20,22) or other means for engaging with. Brakes are threaded over and underneath adjacent racket strings, with each end section attached to one of the strings.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for damping the vibration of a string of tennis rackets.

[0002]

[Prior Art]

 After the tennis ball leaves the string of tennis rackets, the string continues to vibrate at a relatively high frequency. Since these vibrations are felt by the arm, many proposals have been made for means for damping the string vibrations. Basically, these proposals relate to two types: (1) a device placed between adjacent strings to dampen vibrations, and (2) an elongated bar threaded above and below the strings. Is. These devices are usually placed in the edge area of the stringing surface so that they do not contact the ball.

Staufa US Pat. No. 4,180,265 proposes a first type of vibration absorber, in particular an elastomeric viscoelastic coupling element. The element mechanically interconnects a pair of adjacent strings. Crent et al., U.S. Pat. No. 4,609,194, proposes another device of the first type in the form of a highly compressible viscoelastic foam made from two different materials. The foam is compressed and inserted between adjacent strings. Another proposal is disclosed in Bossian U.S. Pat. No. 4,761,007. There, plates inserted between the strings include a centrally lowered weight to dampen vibrations.

A second type of example is disclosed in Adam US Pat. No. 4,575,083 and US Pat. No. 4,732,383. In these cases, an elongated strip of vibration absorbing material is threaded over and underneath adjacent strings.

[0005]

[Problems to be solved by the device]

 An object of the present invention is to provide a vibration damping device that provides variable vibration damping characteristics over the entire string surface. In particular, the vibration damper of the present invention provides a large damping to the outer longitudinal string and a small vibration damping to the central longitudinal string. Therefore, if the ball hits the outside of the racket, which tends to produce an undesired response, there will be a great deal of braking. On the other hand, if the ball hits the center of the stringed area, it will provide a small amount of braking so that the string remains elastic and well-pushed.

[0006]

[Means for Solving the Problems]

 The vibration damper of the present invention comprises a relatively thin, flexible elastomeric strip having a pair of large mass end sections. Each end section includes a groove or other means for engaging the string. Brakes are threaded over and underneath adjacent racket strings and attached by attaching each end section to one of the strings.

In one embodiment, the end sections are in the form of a pair of donut shaped members, each member having an outwardly facing locking groove in the shape of a keyhole for engaging a string. The donut member and connecting strip taper in width and thickness toward the center, and the device is configured to have the shape of a bow tie. In addition to the holes in the donut member that act to reduce wind resistance, the strips are provided with holes to further reduce wind resistance and increase flexibility. The rate of braking can be varied by changing the spacing and size of these holes.

Preferably, the dimensions of each donut member are sized to fit between two adjacent longitudinal strings. One string is received in the outward facing slot and a second locking slot is provided towards the interior where the donut member and strip join to receive the other longitudinal string. ..

[0009] Preferably, the length of the strip is threaded over and under at least four, and optimally six central longitudinal strings, with each donut member on either side of the outer string of the next pair. It should be the length of the engagement. In this way, a relatively large amount of damping is applied to the four outer strings that engage the donut member, and a small vibration damping is applied to the central string.

In order that the present invention may be better understood, the present invention will be described below with reference to the illustrated embodiments.

[0011]

【Example】

 The vibration damper 10 includes a relatively thin flexible strip 12 and large mass donut shaped members 14 at opposite ends thereof. Preferably, the brake 10 is made as a thermoplastic elastomer, for example about 50 Shore A durometer, although other materials and durometer hardness can be used.

As one example, the width w-w (FIG. 1) and thickness t-t (FIG. 2) of the brake 10 taper toward the center plane 16 so that the brake 10 is generally bow tie. The connecting strip 12 is thinnest and is most flexible in the center.

Each donut member 14 has a hole 18 extending at a right angle to the strip 12 and further has an end tightening groove 20 at a right angle to a longitudinal axis 21 of the brake 10. The size of each tightening groove 20 should be such that it accepts a standard tennis string in a keyhole style. Similarly, in addition to the tightening groove 20, there is provided a second pair of tightening grooves 22 parallel to the tightening groove 20, which second tightening groove and the donut member 14 at the top surface 24 and the bottom surface 26 of the brake 10, respectively. Prepare between the strips 12. Due to the presence of the groove 22 as shown in FIGS. 2 and 3, the strip 12 connects the donut members in the area of the reduced thickness t-t to form a flexible joint. Finally, a series of holes 28 are formed through the strip 12 at right angles to the plane of the strip 12 to reduce wind resistance and increase flexibility. The size and spacing of the holes 28 can be varied as needed to change the braking action.

As an example of the approximate dimensions, the brake has a total length of 95.5 mm. The strip 12 has a length of 58 mm and has a width tapering from 14 mm at the fastening groove 22 to 6 mm at the center 16 and a thickness decreasing from 3.8 mm near the groove 22 to 3.0 mm in the central area. With. The donut member 14 has a length of 22 mm (along the axis 21), tapering from 10.7 mm to 8.8 mm (towards the center of the brake) and from 17 mm to about 14 mm connecting with the strip 12. Has a width of. As shown in FIG. 1, the widths w-w of both the donut member 14 and the strip 12 are continuous with a constant taper towards the center plane 16. Preferably, the strip 12 and the donut member 14 are molded in a one piece structure, but they may be molded separately.

A preferred method of using the brake 10 is shown in FIG. This figure shows a portion of the tennis racket frame 30 in the area of the throat bridge section 32. FIG. 4 shows a number of vertical or "main" strings 34 and a bottom transverse string 36. The strips 12 are alternately sewn above and below adjacent strings 34 so that the donut member 14 is placed between a pair of outer main strings 34a, 34b. The string 34a is pushed into the tightening groove 20 of each member 14 and the string 34b is appropriately received in the upper or lower tightening groove 22. Preferably, the damper 10 is centered with respect to the two most central main strings 34c and the racket axis 40 and just below the lowermost lateral string 36.

The strip 12, especially near the center, is flexible and has a relatively low mass, so that it has a smaller damping effect than does the donut member 14. Thus, the main strings 34c, d, and especially the most central string 34c, are springy and elastic. The donut member 14 damps the string vibration of the outer strings 34a and 34b more effectively. Therefore, if the ball hits the strings 34a, b, or hits the racket with more outer strings (ie, such strings are connected to the string 34a to some extent by the transverse strings), the perimeter or outside of the string surface is More effectively braked. This is advantageous because it is the ball that hits the outside of the racket that tends to produce an undesirable response. Therefore, it is most desirable to produce a large braking action in these areas.

5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B are diagrams of the response of a tennis racket with a brake 10 of the present invention and a string vibration test comparing a racket without such a brake. Is. In each test, the racket head was fixed so that the vibration of the string was isolated as much as possible. When testing a racket with the brake 10, the brake was mounted on the main string as shown in FIG.

5A, 5B, 6A, 6B show the response of the central longitudinal string 34c to the impact of a ball. 5A and 5B show that the total vibration level is reduced and is rapidly damped when using the brake of the present invention. Specifically, FIGS. 6A and 6B show changes in the characteristic vibration frequency.

When the ball hits the string as shown in FIG. 6A, it is shown that vibrations occur at various frequencies. The maximum amplitude occurs at 1290 Hz, and other important peaks occur at about 580 Hz, 950 Hz, 1450 Hz, etc. On the contrary, in FIG. 6B, the maximum peak occurs at 580 Hz and the peak occurs at other frequencies which are significantly reduced. As described below, reducing these high frequencies and concentrating the string's oscillatory response at low frequency levels is extremely advantageous.

FIGS. 9, 10 and 11 are computer-generated diagrams showing the fundamental frequency (618 Hz) and three string vibration patterns corresponding to two high-order frequencies (972 and 987 Hz). These frequencies occur for the particular dimensions, string patterns and tension of the test racket.

At the fundamental frequency shown in FIG. 9, the string bed acts as a single film moving in and out of the string plane at rest, ie, responding in a “cupping” mode. In contrast to the fundamental vibration modes shown in FIGS. 10 and 11, the high order vibration modes produce a non-uniform string bed response, causing some directional error in the flight of the bouncing ball.

FIG. 6B shows that the inventive brake 10 significantly dampens high order vibration modes, while maximizing the predominant cupping mode. Thus, in addition to the improved vibration dampening capability shown in FIG. 5B, the present invention has the advantage of producing a more advantageous string bed response by selectively reducing high levels of vibration.

7A, 7B, 8A, 8B show the response of a main string, eg, string 34a, to ball impact measured 2 inches from the center. 7A and 7B show that the vibration is damped more rapidly using the brake of the present invention. Moreover, as shown in FIGS. 8A and 8B, high level vibration frequencies are significantly reduced.

Another method using a brake is shown in FIG. This figure shows a teni racket including a frame 30. A pair of brakes 10 are mounted on the cross string 38 at the 3 o'clock and 9 o'clock positions in the area of the racket's widest portion. Since the brakes provide the greatest braking adjacent to the donut member 14 than in the center, the brakes mounted on the transverse strings so that they extend parallel to the racket axis 40 hit the tip and near the throat. It has the advantage of giving a small amount of braking to the ball hitting the center of the racket. Preferably, the main string brake 10 can also be used as shown in FIG. 12 when using one or more cross string brakes.

Although only one transverse string brake can be used, preferably one pair is used for balancing as shown in FIG. This gives the additional advantage of increasing the polar moment of inertia by only 0.20 gm ² . This increases stability by roughly 10-15%.

The preferred embodiment of the present invention has been described above, but the present invention can be variously modified within the scope of the invention. For example, other shaped strips or weighted end members could be used to provide variable string damping. The end members can also be hooked into a large number (or a small number) of strings. Also, various materials can be used for the end members, and vibration absorbing materials can be used instead of using a large mass for the end members to achieve the desired vibration reduction. All of these changes are included in the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a front view of a vibration damper according to the present invention.

FIG. 2 is a side view of a brake.

3 is an enlarged sectional view taken along line 3-3 of FIG.

FIG. 4 is a front view of a portion of a tennis racket having a vibration damper attached thereto.

FIG. 5A is a plot of center string vibration versus time for a racket without a vibration damper of the present invention.
(B) is a diagram of center string vibration versus time for a racket with a vibration dampener of the present invention.

FIG. 6 (A) is a chart of vibration frequency distribution for a central string of a racket without a brake. (B)
FIG. 3 is a chart of vibration frequency distribution for a central string of a racket with a braking device.

FIG. 7A is a diagram corresponding to FIG. 5A of vibration at a position separated by 2 inches from the central vertical axis. FIG. 5B is a chart corresponding to FIG. 5B of vibration at a location separated by 2 inches from the central vertical axis.

FIG. 8A is a chart corresponding to FIG. 6A of the vibration frequency distribution at a location separated by 2 inches from the central vertical axis.
FIG. 6B is a chart corresponding to FIG. 6B of the vibration frequency distribution at a location separated by 2 inches from the central vertical axis.

FIG. 9 is a computer generated chart of a string vibration pattern at a frequency.

FIG. 10 is a computer generated chart of string vibration patterns at other frequencies.

FIG. 11 is a computer generated chart of string vibration patterns at yet another frequency.

FIG. 12 is a front view of a tennis racket showing brakes attached to both the main string and the lateral strings.

[Explanation of symbols]

 10 Vibration Damper 12 Strip 14 Donut Shaped Member 20 End Tightening Groove 22 Tightening Groove 28 Hole 30 Tennis Racket Frame 34 Main String 36 Horizontal String 38 Horizontal String

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[Procedure amendment]

[Submission date] April 21, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Item name to be amended] Scope of utility model registration request

[Correction method] Change

[Correction content]

[Scope of utility model registration request]

 ─────────────────────────────────────────────────── ————————————————————————————————— 72 Known A. Stevens, USA Pennsylvania 19446 Landsdale Brook Circle 105

Claims (20)

[Scope of utility model registration request] 1. A vibration absorber for a sports racket having a string defining a string tension surface, comprising an elongated member including a flexible thin connecting portion for damping relatively small vibrations, and the connecting portion. Vibration damping means provided at opposite ends of said elongated member for damping large vibrations, said vibration damping means including means for releasably engaging at least one string, said member comprising: Threaded through the top and bottom, the connecting portion contacts at least two strings and each vibration damping means contacts at least one other string to provide variable vibration damping along the string tension surface. Vibration absorber characterized by having done. 2. The vibration absorber of claim 1, wherein the vibration dampening means comprises an end member having means for engaging a length of string in frictional contact with the string. 3. The vibration absorber of claim 2, wherein the means for engaging the length of string is in the form of means for anchoring each end member to the string by frictional contact. 4. The size of each end member is sized to fit between a pair of adjacent parallel strings of tennis rackets so that both sides of the end member frictionally contact two parallel strings.
The vibration absorber according to claim 3. 5. The vibration absorber of claim 4, wherein the means on the end member for engaging the string comprises an outward clamping groove. 6. The vibration absorber of claim 5, wherein the end members have a relatively greater mass per unit length than the connecting portion. 7. Each end member includes a second fastening groove on a side opposite the outward fastening groove, the outward fastening groove and the second fastening groove engaging a pair of parallel strings. 7. The vibration absorber according to claim 6, wherein the vibration absorbers are separated from each other by a distance suitable for 8. A vibration absorber for a tennis racket having a central main string and an external main string,
A strip of relatively thin elastomer having a length greater than the distance between the central main strings and a pair of end sections having a relatively large mass, each end section being a length of string for frictional contact. The engaging means on the opposite end sections are separated by a distance approximately equal to the distance between the pair of outer main strings, and the vibration absorber is threaded above and below the main strings. And the strips are brought into contact with the central main string and the end sections are hung on a pair of outer strings, the vibration absorber thus being more in the string outside the central main string. A vibration absorber characterized by giving large vibration damping. 9. The vibration absorber of claim 8 wherein the strip has a length and extends above and below at least four adjacent central main strings. 10. Each end section is adapted to fit between a pair of first and second outer strings for frictional contact with both strings, the first outer string of the pairs being the aforesaid strings. 10. A vibration absorber as claimed in claim 9 which is located further from the racket axis than the second outermost string of the pair and the engagement means on each end section is adapted to engage the first outermost string. .. 11. The vibration absorber of claim 10, wherein each end section includes means for engaging a second outer string. 12. Each end section includes a donut shaped member, the engaging means defining an outward clamping groove in the donut member, and the means for engaging the second outer string is the junction point of the donut member and the strip. Second formed on
The vibration absorber according to claim 11, which comprises a tightening groove. 13. The fastener groove of claim 12, wherein the fastening groove comprises a keyhole-shaped groove defined by an outwardly opening slot, the slot having a hole sized larger than the slot for seating a string. Vibration absorber. 14. The vibration absorber of claim 13, wherein the strip has a width and thickness tapering toward the center so as to form a bow tie shape. 15. A vibration absorber for a sports racket having a string that defines a stringing surface, comprising an elongate flexible member sewn over and under at least four strings, said member comprising at least four strings. Having at least one string receiving groove for positively frictionally engaging a length of string when threaded into the string, the member having at least two string grooves when threaded into the string. A vibration absorber characterized in that it makes variable vibration damping along the string tension surface by contacting with other strings without positive frictional engagement. 16. The member has a second string receiving groove, the string receiving grooves being parallel to each other and spaced apart from each other by a distance for receiving a pair of adjacent parallel strings. The vibration absorber according to item 15. 17. A method of damping string vibrations in a tennis racket having a main string including a central string and a plurality of transverse strings, the method comprising: (a) vibration in the form of an elongated member including a pair of end portions and a connecting portion. An absorber, (b) threading the elongate members above and below adjacent strings, (c) anchoring the end portions to the first pair of strings so that the connecting portion contacts another string, ( d) A method comprising the step of providing means on said end portion for damping a first pair of strings more than other strings. 18. The end portion has a greater mass per unit length than the connecting portion, and further comprising the step of positioning the elongated member such that the connecting portion contacts the pair of central main strings and the end portion is 18. The method of claim 17, adapted to engage a pair of outer strings. 19. The method of claim 18, wherein the connecting portion contacts the central main string of at least one additional pair. 20. The method of claim 18, wherein the connecting portion contacts the central main string of at least two additional pairs.