KR20160005121A - Racquet having elongated grommet barrels with improved damping characteristics - Google Patents

Abstract

Sports racquets with improved string vibration damping have grommets with barrels stretched over many of the crossstrings. The inner diameter of the barrel is selected to preserve the minimum spacing between the crossstring and the cover barrel, thereby relieving vibration. The barrel length varies as a function of distance from the top of the frame so that the free ends are located near the nearest main string.

Description

[0001] RACQUET HAVING ELONGATED GROMMET BARRELS WITH IMPROVED DAMPING CHARACTERISTICS [0002]

The present invention relates to sports racquets comprising a grommet with a plurality of crossstrings having a vibration-attenuated extended barrel.

Today's sport racquets, such as tennis, racquetball, squash and badminton racquets, each have a frame with a head portion that supports a string bed, coupled to a shaft or handle. The size and length of the head vary depending on the specific sport in which the racquet is used. As the racquet charges a ball or a figurine such as a shuttlecock, the string deflects from the racquet and drives the figurine, but the string vibrates after the initial impact. The resulting string vibrations are transmitted to the frame of the racket and eventually to the handle or shaft and finally to the user's hands, arms and shoulders. Such string vibrations can cause inconvenience to the user or an impression of an incorrect response to the ball response.

Vibration damping devices have been incorporated into racquets in an effort to absorb and reduce these vibrations, which can result in reduced performance due to inaccurate feel, inconvenience or fatigue. While there are many other types of attenuation devices, most try to absorb vibration in the string bed before being transmitted to the frame. Many such devices consist of a rubber or silicone material that attaches to a string at or near the throttle of the racket and absorbs vibration. Because these devices must be lightweight to at least affect the balance and feel of the racket, and because many of them are located remotely from the main racket price area, they can provide sufficient attenuation to significantly reduce vibration none. Also, many are difficult to install and some tend to degrade during operation.

However, grommets are generally incorporated into racquets to prevent premature string wear. Thus, a lightweight attenuation device in the vicinity of the price area, in the form of an elongated grommet consisting of an elastic material which minimally affects the weight, balance and feel of the racket but which significantly reduces unwanted vibrations in the string bed It may be advantageous to merge. Such vibrations as felt are better correlated to how well the ball is priced, and should be more uniform between the center and off-center prices.

The inventor previously introduced racquets in which several of the grommets extended into the string bed as barrels, which had a beneficial vibration-damping effect. However, it has been found that extending these barrels further generates additional and unpredictable vibrations that reduce from optimal feel by the user. Therefore, there is a continuing need for improvements in vibration damping and stability in sports racquets.

It is an object of the present invention to provide a sports racket improved in vibration damping and stability.

Accordingly, the present invention provides a sports racket comprising a grommet having a plurality of crossstrings having a vibration-attenuated extended barrel. Preferably, the plastic barrel extends from the boundary constituted by the string bed to the string bed, so that at least about 75% of the crossstring from the crossstring boundary to the first main string is covered. Alternatively, the free end of the barrel is disposed to be less than about 15 mm from the nearest main string. The string gauge and the inner diameter of the barrel are selected as having an interval of at least 0.14 mm, preferably at least 0.16 mm, and more preferably at least 0.19 mm between the inner surface of the barrel and the outer surface of the string. Alternatively, the inner diameter of the barrel may be at least 21% greater than the outer diameter of the string, and more preferably at least 33% greater than the outer diameter of the string. If at least this amount of spacing is maintained, the result was found to be an attenuated racquet with good stability and no unwanted "buzz" or undamped vibrations. The barrel may be formed integrally with one or more grommet strips positioned adjacent the grommet hole of the frame, preferably outside the frame. In order to bring the free end of the grommet barrel closer to the nearest main string, the length of the barrel on any one grommet strip increases, though not always, as it progresses from the top of the frame head to the throat.

The present invention provides a sports racquet improved in vibration damping and stability.

Other aspects and advantages of the invention can be seen in the following specific description, wherein like reference numerals denote like parts, and wherein:
1 is an isometric view of a sports racquet representing a head, a handle, a string bed, and a grommet according to the prior art;
2 is a plan view of a sports racket according to a first embodiment of the present invention;
Figure 3 is a plan view of a second embodiment of the present invention wherein most of the crossstrings are covered or enclosed by long-barrel grommets having free ends within a predetermined distance of the nearest main string;
Figure 4 is a side view of a prior art grommet strip with a grommet having a short barrel;
Figure 5 is a side view of a grommet strip with a grommet having an elongated barrel;
Figure 6 is a side view of a grommet strip with a drawn barrel and a grommet having a varying length, and once the grommet strip is installed, the end of the barrel is positioned at a more constant distance from the nearest main string;
Figure 7 is a detail view of an individual gromit having an elongated barrel;
Figure 8 is a cross-sectional detail view taken substantially along line 8-8 of Figure 3;
Figure 9 is a cross-sectional view taken substantially along line 9-9 of Figure 8;
10 is an isometric view of a test fixture used to test the vibration damping effect of the present invention;
Figure 11 is a top view of the test fixture;
Figure 12 shows the relationship between the vibration intensity versus time for a racquet substantially as shown in Figure 2, connected by a 16 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball fell onto the center of the string bed. ≪ / RTI >
Fig. 13 is a graph showing the vibration intensity versus time for a racket substantially as shown in Fig. 3, wherein the barrel is set at 1.5 < RTI ID = 0.0 > Connected with a 16 gauge string with an internal diameter of -1.6 mm;
Figure 14 is a cross-sectional view of the barrel shown in Figure 3, in which the barrel is connected with a 16 gauge string with an inner diameter of 2.6 mm, as measured using the test fixture of Figures 10 and 11 after the ball has fallen into the center of the string bed ≪ / RTI > for a racket such as a bar;
Figure 15 shows the vibration intensity versus time for a racquet substantially as shown in Figure 2, connected by a 17 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball fell to the center of the string bed ≪ / RTI >
Fig. 16 is a graph showing the vibration intensity versus time for a racquet substantially as shown in Fig. 3, wherein the barrel is positioned in the center of the string bed, as measured using the test fixation of Figs. 10 and 11, Connected by a 17 gauge string with an internal diameter of 1.5-1.6 mm;
Figure 17 shows a barrel having an inner diameter of 2.6 mm and connected by a 17 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball fell to the center of the string bed, A graph showing the vibration intensity versus time for the same racquet;
Figure 18 shows the vibration intensity versus time for a racket substantially as shown in Figure 2 connected by an 18 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball fell onto the center of the string bed ≪ / RTI >
FIG. 19 is a graph showing the vibration intensity versus time for a racket substantially as shown in FIG. 3, wherein the barrel is positioned in the center of the string bed, as measured using the test fixture of FIGS. 10 and 11, Having an internal diameter of 1.5-1.6 mm and connected by an 18 gauge string;
Figure 20 is a cross-sectional view taken substantially parallel to Figure 3 with a barrel having an inner diameter of 2.6 mm and connected by an 18 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball has fallen into the center of the string bed. ≪ / RTI > for a racquet such as that shown in FIG.
Fig. 21 is a side view of a racquet substantially as shown in Fig. 2, connected with a 16 gauge string, as measured using the test fixture of Figs. 10 and 11 after the ball has fallen into the string bed at a predetermined off- A graph showing vibration intensity versus time;
FIG. 22 is a graph showing the vibration intensity versus time for a racquet substantially as shown in FIG. 3, and after the ball has fallen to the string bed at a predetermined off-center location, the barrel has been tested using the test fixation of FIGS. 10 and 11 Connected as a 16 gauge string with an internal diameter of 1.5-1.6 mm as measured;
Figure 23 shows a barrel having a barrel connected with a 16 gauge string with an internal diameter of 2.6 mm, as measured using the test fixture of Figures 10 and 11, after the ball has fallen onto the string bed at a predetermined off- 3 is a graph showing the vibration intensity versus time for a racquet as shown in FIG. 3; FIG.
Fig. 24 is a graph showing the vibration intensity versus time for a racket substantially as shown in Fig. 2, after the ball has fallen to the string bed at a position deviated from a predetermined center, and measured using the test fixation of Figs. 10 and 11 Connected as a 17 gauge string, as shown;
Figure 25 shows a barrel having an inner diameter of 1.5-1.6 mm and connected in a 17 gauge string, as measured using the test fixture of Figures 10 and 11, after the ball has fallen onto the string bed at a predetermined off- , A graph representing vibration intensity versus time for a racquet substantially as shown in Figure 3;
Figure 26 shows a barrel having a barrel connected with a 17 gauge string with an internal diameter of 2.6 mm, as measured using the test fixture of Figures 10 and 11, after the ball has fallen onto the string bed at a predetermined off- ≪ / RTI > for a racquet as shown in Figure 3;
Figure 27 is a side view of a racquet substantially as shown in Figure 2, connected with an 18 gauge string, as measured using the test fixture of Figures 10 and 11 after the ball has fallen onto the string bed at a predetermined off- ≪ / RTI > is a graph showing the strength vs. time for vibration;
Fig. 28 is a graph showing the vibration intensity versus time for a racquet substantially as shown in Fig. 3, in which the barrel uses the test fixture of Figs. 10 and 11 after the ball has fallen onto the string bed at a position deviated from a predetermined center , With an internal diameter of 1.5-1.6 mm and connected as an 18 gauge string; And
Figure 29 shows a barrel having an inner diameter of 2.6 mm and connected as an 18 gauge string, as measured using the test fixture of Figures 10 and 11, after the ball has fallen into the string bed at a predetermined off- 3 is a graph showing the vibration intensity versus time for a racquet as shown in FIG.

1, a sports racket, generally indicated at 100, includes a frame 102 having a handle 103, a head 104, a string bed 105, and at least a portion of the head 104 And has a plurality of grommet holes 106 arranged around it. The frame 102 is formed to exclude any throat pieces (not shown) or other structures in the throat area of the racquet and engages the head 104 and handle 103 or shaft. The string bed 105 substantially stays in the string bed plane P. [ The string bed has a plurality of crossstrings 107 transversely transverse to the head 104 of the racquet 100 and a plurality of main strings 108 longitudinally transverse to the head 104. The crossstrings 107 intersect the main string 108 at significant angles and cross the racquet longitudinal axis X (Figs. 2 and 3) at a generally 90 degree angle. Although the cross string 107 and the main string 108 are referred to as separate strings in the discussion below, each of the cross string 107 and main string 108 is a longer string or string used to connect the racket 100, Lt; / RTI > Any limitations on the string bed, the string itself, the number of strings, the diameter, or the length, the connectivity of the strings, the string physical or chemical composition, or any other string quality are not individually deduced by discussion of the strings. Thus, each crossstring 107 and main string 108 may have the same diameter as another string or may have a unique separating string diameter. The crossstrings 107 are generally parallel and spaced from one another.

The crossstrings 107 extend between and enter each grommet hole 106. The frame head 104 has a laterally inwardly facing surface 112. The string bed boundary 111 is defined as the intersection of the plane P with the surface 112. Each of the grommet holes 106 is adjacent a string bed boundary 111. One or more grommet strips 109 can be adjacent to the grommet hole 106 and are typically assembled laterally outside the frame 102.

As shown, the sports racket 100 is configured such that most or all of the main string 108 is fed to the hollow handle 103 and is anchored to the anchor (not shown) at or near the handle end 110, Type racquetball racquet or some or all of the main string 108 may be of a more conventional type having a lower anchoring point on the frame 102 or throat piece (not shown). The invention can also be used in other racquets such as those used in tennis, badminton or squash. If one end of the main string 108 is fed into the hollow handle, the opposite end will extend into the grommet hole 106 on the top of the racquet. Otherwise, the main string 108 will extend between the grommet holes 106 and enter them. In this racquet 100, each of the grommet holes 106 is formed by a grommet that does not perceptibly extend to the string bed, since the primary purpose is to act as a bushing for the string as the string is routed through the frame 102 It is tailored.

Referring to FIG. 2, a sports racket of the type of FIG. 1 is shown, but a portion of the grommet that includes or configures the barrel 202 is disposed on the seventh crossstring 107. Barrel 202 is medium and usually of uniform length. The racket 200 of the type shown in FIG. 2 is sold by the applicant under the trade mark "Heatseeker 2.0 ". The racquet has a barrel 202 extending about 29 mm from the junction with the grommet strip 109 to the free end 204 and extending into the string bed 105 to a substantially uniform 26 to 27 mm. The free ends 204 are disposed at a distance that varies greatly from the nearest or most lateral main string 210 (i.e., the main string closest to the string bed boundary 111) Off is in the range of zero to 18 mm or more. The crossstring 107 covered by the barrel 202 may constitute a portion of a "sweet spot ", the center of which may be a point on the racquet or a point on the center 206 or a racquet string Bed 105. < / RTI > The sweet spot is a general area on the string bed 105 where the coefficient of restitution is closest to, or maximum, Sweet spots can vary depending on user, string tension, material, string type, frame composition, and operating style. For the test described below, however, the sweet spot center 206 was in the same position in terms of distance from the frame top 212 and was always controlled to be on the racquet longitudinal axis X. [ Also shown in FIG. 2 is an intentional off-center target 208 displaced towards the handle 103 and off-axis. The position of the target 208 was controlled to remain the same from one racket to the next for the off-center ball drop test shown by Figures 21-29.

3 shows sport racquet 298 with long barrel grommets 300-320 of substantially different lengths and free end 324 tends to be placed closer and at a greater distance from the nearest main string 210 have. In one embodiment, the barrel is in the length range from about 24 to 26 mm in the top-coated string (barrel 300) to about 39 to 42 mm in the bottom-covered string (barrel 320). These barrel lengths are measured from the point at which the string bed boundary 111, or string, escapes from the inner side wall 112 of the frame 102 to the free end 324 of the barrel. The distance between the free end 324 of the barrel and the nearest main string 210 also has a tendency to increase (with some exceptions) as the handle 103 is approached. This distance may be as short as about 2 mm in barrel 300 and as long as 15 mm in barrel 318. In one embodiment, the range of distances may be between 2 mm and 13 mm. It is preferable that the seventh or more crossstrings 107 can be covered and most of the crossstrings 107 are covered or mounted with long barrels. In the embodiment shown in Fig. 3, the eleventh cross string 107, or the fifth through fifteenth cross strings 107, have end segments that are mostly surrounded or covered by the barrels 300-320.

The amount of cross string 107 (sometimes "outer length" of the string as used herein) of the inner racket frame sidewall 112 covered by the barrel to the nearest main string 210 is also determined by the barrel 300, Lt; RTI ID = 0.0 > 320 < / RTI > The barrel 300 covers as much as 90% of the outer length of the string 107; Barrel 318 covers less than 75% of the outer length of each crossstring 107. More preferably, such coverage is in the range of about 76% to 90%. The percentage of coverage has a tendency to fall as one approaches the handle 103.

Referring to FIG. 4, a prior art grommet 401 that has not been stretched with a vibration damping barrel is attached to prior art grommet strip 109. The prior art grommet 401 is generally of a length extending from the string bed boundary to the string bed by about 3 mm. The length of the prior art grommet 401 is typically selected to be sufficient to extend through the frame 102 in each grommet hole 106. [ While the grommet 401 is shown as being of uniform length, the length can be variable if the racquet head cross-sectional thickness varies with position.

Referring to FIG. 5, the grommet strip 500 was attached to a vibration attenuating grommet 501 having an intermediate stretched barrel 503. The primary purpose for the stretched grommet barrel 503 is to attenuate the vibration of the string bed 105 when the string bed 105 impacts the corpus. This force is transmitted to the head 104 of the racquet 100 and finally to the user when the string bed 105 receives the vibratory force from the impact of the paraplegic body. The grommet 501 may also act to create a more stable working surface. Also shown in the illustrated embodiment of the grommet strip 500 is a grommet 502 that does not have an elongated barrel. The grommet strip 500 may comprise a combination of a grommet 501 having a short grommet 502 and an elongated barrel 503. Each grommet 501 having an elongated barrel 503 extends from the string bed boundary 111 by about 0.55 inches to the string bed 105. In the commercial "heat seeker 2.0" tested below, the grommet 501 extends from the string bed boundary 111 to the string bed 105 by about 26.7 to about 28.2 mm, each of which, as measured from the grommet strip backing It is slightly longer than about 29mm.

A set of three improved grommet strip segments is shown in FIG. The grommet strip segment 600a has an integrally molded barrel 300-320. The grommet strip 600a will be assembled on the left side of the racquet 298 and accommodates eleven cross-section strings 107. Barrel 300-320 has a generally increasing length as a function of distance from frame top 326 and as a function of increasing proximity to handle 103, as measured from the appropriate segment at the free end. In the commercial embodiments tested below ("Invasion" and "Invasion X"), the barrel 300-320 has a diameter of 27.6 mm, 30.4 mm, 33.0 mm, 35.6 mm, as measured from the grommet strip to the free end , 37.7 mm, 39.3 mm, 42.8 mm, 42.9 mm, 42.5 mm, 42.9 mm, and 43.0 mm, respectively. The barrels 312-320 are approximately the same length while the length of the barrels 300-310 increases more rapidly as a function of distance from the top 326 of the frame. As inserted into the grommet hole 106, these variations in barrel length will be filled as it progresses through the frame 102. As such, the length of the barrels 300-320 as measured from the string bed boundary 111 to the free end 324 will exhibit more variation as installed. The strip segment 600a terminates at the end adjacent the barrel 300 with the grommet 602 without an extended barrel. This end grommet 602 receives a peg or sleeve 604 of the head grommet strip segment 606. The head grommet strip segment 606 has no stretched barrel on it in the illustrated embodiment. The grommet strip segment 606 is assembled to the frame 102 around the top of the head 104. The same grommet strip 600b as the previously described grommet strip segment 600a is provided on the right side of the racquet frame 102. [ At the location of the three grommet strip segments 600a, 606, 600b, an integrated grommet strip may be provided, or more grommet strip segments may be provided for convenience in modeling or assembly.

Referring to FIG. 7, a single grommet 700 having an elongated barrel 702 may be provided separate from the multi-grommet grommet strip segment 600a, 600b. In either case, any one of the barrels 300-320 on the single grommet 700 and the grommet strips 600a, 600b can be used to inject the barrel inner diameter 704 and the barrel- And preferably has a slightly tapered outer diameter for ease of handling. Individual grommets 700 may extend through each grommet hole 106 (FIG. 2). The racquet 298 according to the present invention may be provided with one or more grommet strip segments such as grommet strip segments 600a, 600b, a plurality of single long-barrel grommets 700, or both. It is contemplated that the grommets or barrels 700,300-320 are located on many, and preferably most, of the crossstrings 107 of the racquet 298.

Referring to Fig. 8, the illustrated and tested frame 102 is a dual barrel frame, but no limitations on the type of frame can be inferred. The frame 102 has a grommet hole 106 into which a grommet having an elongated barrel 800 is inserted. The long barrel grommet includes the cross string 107 in close proximity. For purposes of the present invention, the grommet barrel will be considered to include the string 107 in close proximity if it has a vibration-damping effect. Referring to FIG. 9, the string 107 has an outer diameter 900. Common string sizes used in sport racquets are 18 gauge with an outer diameter of 1.22 mm +/- 0.02 mm; 17 gauge with an outer diameter of 1.27 mm +/- 0.02 mm; And a 16 gauge with an outer diameter of 1.32 mm +/- 0.02 mm. For example, the grommet barrel 800, as found for the "Invasion ", and test results shown by Figures 13, 16, 19, 22, 25 and 28, Lt; RTI ID = 0.0 > 704 < / RTI > Therefore, the inner diameter is 1.2 times to 1.33 times the string diameter 900. There will be an interval 902 between the inner wall 904 of the barrel 800 and the surface of the string 107. In the "Invoice" and "Heat Seeker 2.0" embodiments, this spacing is in the range of 0.09 to 0.19 mm. The grommet 800 may be attached to the grommet strips 600a, 600b (FIG. 6) or may be a separate grommet 700 (FIG. 7). The inner diameter of the barrel is preferably at least 21% of the string diameter. In another embodiment, the inner diameter of the barrel may be at least 33% of the string diameter.

In the tested "Invasion X" embodiment, the barrel inner diameter is about 2.6 mm. 18ga-16ga. As with the string, this means that the inner diameter of the barrel 800 is about 1.9 to 2.2 times the outer diameter of the crossstring it contains. For these string gauges, the spacing 902 is in the range of about 0.64 to 0.69 mm. To mitigate the vibration transmitted to the long barrel by the crossstring 107, the gap 902 may be at least 0.14 mm, preferably at least 0.16 mm, and more preferably at least 0.19 mm.

With regard to the composition of the barrel 800, the inventor has determined that a non-brittle polymer that is flexible and does not break the impact of the stencil of the string bed can be used. The polymer may be more flexible than the frame, but still be sufficient plastic to exhibit damping characteristics. Preferably the polymer may have an elastic modulus in the range of 280-1730 MPa as measured under the ISO 178 test method. More preferably, the modulus of elasticity is 390 MPa as measured under the ISO 178 test method. Preferably the polymer may have a Sharpe notch impact strength of about 5 to 125 kJ / m < ² > under the ISO 179 test method. More preferably, the polymer may have a burn blood notched impact strength of 120kJ / m ² and 20kJ / m ² at -30 degrees centigrade at 23 degrees Celsius. Preferably the polymer may not break in the Sarphibinotchi impact strength test under the ISO 178 test method. The preferred polymers may be polyethers with amide blockers, such as the amide formulations sold under the trademark PEBAX 7033 SP1. Another polymer that may be considered is a polyamide such as nylon 11 or a nylon 12 commercially available formulation.

The tested string was an E-Force Oxygen (TM) 16-18 gauge string connected to a final tension of 30 pounds each. The Oxygen ™ string consists of hundreds of synthetic microfibers bonded together.

Referring to Figures 10 and 11, the test apparatus 1000 is configured to perform a test on the vibration damping quality of a grommet having an elongated barrel. A commercial embodiment of racket 200 (Figure 2) and 298 (Figure 3) has been tested. The tested racquet was positioned at fixture 1000 and held in a fixed position. In the fixed position, the racquet frame 102 moves only the string without moving when it is priced with the ball. The propene HD racquetball, having a diameter of 2.5 inches and a weight of 1.4 ounces, dropped from a fixed position height 1002 of 2 feet and was equidistant from both sides of the racket frame and from the top of the frame 102 It was intended to price 4 inches. Vibration was measured through a microphone 1004 (Figure 11) located 5 inches above the string bed directly above the top of the racket frame 102. The microphone 1004 identified the acoustic waveform caused by the vibration when the racket was priced at the ball. The microphone 1004 was connected to a computer using a software bundle called the NCH Audio Essential 2012 edition containing the following sub-programs:

Wave Pad Sound Editor

MixPad Multi-Track Mixer

Record pad sound recorder

Golden Record Vinyl Converter

Switch Audio File Converter

Zulu DJ software.

The two programs used from the above list were Wave Pad and Record Pad.

Referring to Figures 12-29, data was taken for the vibration characteristics of nine different racquets, resulting in both a center drop (on position 206) and a drop on center 208 off position. The center position 206 and off-center position 208 were controlled to be in the same position throughout the test with respect to the degree of lateral displacement from the racket shaft and the degree of longitudinal displacement from the head's upper margin. Throughout the test, a 170 gram racquet was used and the end tension used to connect the racquet was 30 pounds. Three models of racquets differing in length, number and inner diameter of the cross-string barrel were connected by a 16 gauge string (the heaviest), a 17 gauge string followed by an 18 gauge string. The models tested in Figures 12, 15, 18, 21, 24, and 27 were the E-Force Hit Siker ™ 2.0 shown in FIG. The models tested in Figures 13, 16, 19, 22, 25, and 28 were E-Force Invasion ™, shown in Figure 3 with a barrel having an internal diameter of 1.5-1.6 mm. The models tested in Figures 14, 17, 20, 23, 26, and 29 were also E-Force Invasion X ™ as shown in Figure 3, but the barrel has an internal diameter of 2.6 mm. The biggest impact on these audio recordings occurs when a falling ball first charges a string bed, and the small impact on the left side of these events is environmental noise.

In the racket tested in Figure 13, the barrel is significantly longer than those on the racket tested in Figure 12 and there are 22 of them instead of 14. All other variables were controlled to be the same. Figure 13 shows a second peak that is nearly as large as the first peak, and this oscillation takes about 0.3 seconds to significantly attenuate. This long attenuation is felt by the operator as an unwanted buzz.

Fig. 14 shows a racket similar to that tested in Fig. 13, the only difference being that the barrel used in such racquet has an internal diameter of 2.6 mm rather than 1.5-1.6 mm. There is a noticeable increase in damping characteristics and damping is also superior to the shorter- and thinner-barrel versions tested in FIG.

15-17 show similar vibration test data for a racket connected with a 17 gauge string rather than a 16 gauge string. Although the improvement is not as dramatic as that shown for the 16 gauge string, an improvement in attenuation appears further as shown in Fig.

Figures 18-20 record the same data for racquets using 18 gauge strings. Here, increasing the diameter of the longer-length barrel (FIG. 20) produces better attenuation than that produced by the narrow, long barrel shown in FIG. For the corresponding racket connected with a heavier (17 or 16 gauge) string, there is not much contiguous "buzz" shown in FIG. 19 as in FIG. 13 or 16. The inventor believes that this is due to the fact that the spacing of the smaller-diameter strings inside the barrel is greater.

Figures 21-29 display data from intentional off-center prices and correspond to data on the central price shown in Figures 12-20. For each of these experiments, the ball fell to position 208 on the racquet. This set of data is useful for analyzing the "stability" of a racquet, which tends to behave in a more uniform fashion, regardless of where the ball on the string bed is priced. Figures 21-23 are rackets connected in a 16 gauge string and can be compared to Figures 12-14. The difference between the center price on the racket fitted with a narrow and long barrel (1.5-1.6 mm inner diameter; FIGS. 13 and 22) and the off-center price is significant. Increasing the inner diameter of these barrels (Figs. 14 and 23) to 2.6 mm deviates from this difference and thus results in a more "stable" racket result. This effect was most evident in rackets with 16 gauge strings.

Due to differences in the behavior of the 16-gauge, 17-gauge and 18-gauge strings in a narrower, longer barrel with an internal diameter of 1.5-1.6 mm, the data is about 0.14 mm, preferably 0.16 mm, 902 < / RTI > between the inner wall 904 and the string < RTI ID = 0.0 > 107 < / RTI & At intervals below this threshold, and with long barrels, a buzz that interferes and insufficiently attenuates is obtained; At more than this interval, these buzzes disappeared.

The improved vibration damping and stability of these racquets have been qualitatively proven by operating them. A racquet with an improved vibration-attenuating barrel improves racket stability while reducing damage to the operator's hands, arms and shoulders and provides more comfort and reproducibility during operation.

In summary, the claimed invention provides increased vibration damping and stability while minimally affecting the weight and balance of the racquet. While the illustrated embodiments of the invention are illustrated and described in the accompanying drawings, the invention is not limited thereto but is limited only by the scope and spirit of the appended claims.

Claims (37)

Wherein the head of the racket frame laterally surrounds the string bed and the head has a lateral inner surface and the string bed stays in the string bed plane and the string bed boundary is formed by the intersection of the head and the inner surface of the string bed plane Said racquet frame having an axis;
A plurality of spaced apart grommet holes formed through the frame and disposed about at least a portion of the head;
A cross string is connected at an angle to the axis, connected in spaced relation to each other and connected to the main string, at least a portion of the cross string being received in each grommet hole in the head, A string bed having a plurality of strings including a main string and a cross string formed to extend between the crossing of the string bed boundary and the cross string with the nearest main string,
Wherein each of said grommet holes is provided with a grommet and wherein a plurality of stretched vibration-attenuating barrels are formed as part of one of said grommets, each barrel comprising a respective contained crossstring, each barrel having a grommet hole And extending to said string bed, said barrel covering at least about 75% of said outer length. The method according to claim 1,
Wherein the barrel covers between about 76% and about 90% of the outer length of the included crossstring. The method according to claim 1,
Each said barrel having an inner wall having an inner radius and said crossstring having an outer surface with an outer radius and wherein the difference between said inner radius and said outer radius is preselected to be at least about 0.14 mm Sports racket. The method of claim 3,
Wherein the difference between the inner radius and the outer radius is preselected to be at least about 0.16 mm. 5. The method of claim 4,
Wherein the difference between the inner radius and the outer radius is preselected to be at least about 0.19 mm. 6. The method of claim 5,
Wherein the difference between the inner radius and the outer radius is preselected to be in the range of 0.64 mm to 0.69 mm. The method according to claim 1,
Wherein each of said crossstrings connected to said racket is connected via at least one of said barrels. The method according to claim 1,
Wherein each of the seventh or more crossstrings connecting on the racket is connected through at least one of the barrels. The method according to claim 1,
Wherein the barrel is provided in pairs and one barrel of each pair extends from the frame on one side of the string bed to the string bed and the second barrel of the pair extends from the frame on the opposite side of the string bed, To the string bed, each cross-string extending through a respective pair of barrels. The method according to claim 1,
Each barrel having an inner diameter and each of the crossstrings having an outer diameter and wherein the inner diameter of the barrel is greater than the outer diameter of the crossstring included by the barrel by at least 21% Sports racket. 11. The method of claim 10,
Wherein the inner diameter of the barrel is greater than the outer diameter of the crossstring included by the barrel by at least 33%. 12. The method of claim 11,
Wherein the inner diameter of the barrel is in a range of about 1.9 to about 2.2 times the cross-string diameter. The method according to claim 1,
Wherein the plurality of barrels are formed integrally with a grommet strip disposed laterally outwardly of the frame. 14. The method of claim 13,
Wherein the racquet frame has an upper portion and the barrel is formed on the grommet strip having a generally increasing length as a function of the distance of the barrel from the upper portion of the racquet frame. 14. The method of claim 13,
Wherein the first and second grommet strips are disposed on opposite sides of the frame and the plurality of stretched barrels are formed integrally with and extend from the respective grommet strips. The method according to claim 1,
The racquet frame having an upper portion and the plurality of barrels comprising a spaced array of barrels comprising respective crossstrings wherein the length of the barrels in the array is a function of the distance of the barrels from the upper portion of the frame Wherein the weight of the racquet is generally increased. The method according to claim 1,
Wherein each stretched barrel comprises a material essentially consisting of a polyether having an amide blocker. The method according to claim 1,
Characterized in that each stretched barrel is made of a material essentially consisting of polyamide. The head laterally surrounding the string bed, the head having a laterally inner surface, the string bed remaining in the string bed plane, and the string bed boundary being formed by the intersection of the lateral inner surface of the head and the string bed plane A racquet frame having an axis;
A plurality of spaced apart grommet holes formed through the frame and disposed about at least a portion of the head;
The crossstrings are connected at an angle to the axis, connected in spaced relation to each other, and connected to cross the main string, at least a portion of the crossstring being received in each grommet hole in the head, And a string bed having a plurality of strings including a main string and a cross string, the outer length being formed to extend between the crossing of the string bed boundary and the cross string having the main string closest to the string bed boundary As a sports racket,
Wherein a plurality of grommets are inserted into the grommet hole and a plurality of stretched vibration-attenuating barrels are formed as part of one of the grommets, each barrel having a free end and comprising each contained crossstring, each Wherein the barrel of the barrel extends through the grommet hole and extends to the string bed so that the free end of the last barrel is at least about 15 mm from the main string closest to the string bed boundary. 20. The method of claim 19,
Wherein said free ends of said barrel are respectively displaced from said nearest main string by a distance in the range of about 2 mm to about 13 mm. 20. The method of claim 19,
Wherein the grommet having an elongated barrel is disposed on at least the eleventh crossstring. 20. The method of claim 19,
Wherein the plurality of barrels are formed integrally with a grommet strip disposed laterally outwardly of the frame. 20. The method of claim 19,
Wherein the first and second grommet strips are disposed on opposite sides of the frame and each of the plurality of the stretched barrels is formed integrally with each of the first and second grommet strips. 20. The method of claim 19,
Characterized in that each said elongated barrel is made of a material essentially consisting of a polyether having an amide blocker. 20. The method of claim 19,
Characterized in that each of said stretched barrels is made of a material essentially consisting of polyamide. 20. The method of claim 19,
Wherein the crossstring has a predetermined diameter and the inner diameter of each barrel is at least 21% greater than the crossstring diameter included. 27. The method of claim 26,
Wherein the inner diameter of each barrel is at least 33% larger than the cross-string diameter. 28. The method of claim 27,
Wherein the inner diameter of each of the stretched barrels is in a range of about 1.9 to about 2.2 times the cross-string diameter. 20. The method of claim 19,
Wherein the distance between the inner surface of each elongated barrel and the outer surface of the crossstring included by the last elongated barrel is at least 0.14 mm. 30. The method of claim 29,
Wherein the spacing between said inner surface of each elongated barrel and said outer surface of said crossstring included by the last elongated barrel is at least 0.16 mm. 31. The method of claim 30,
Wherein the spacing between the inner surface of each elongated barrel and the outer surface of the crossstring included by the last elongated barrel is at least 0.19 mm. 32. The method of claim 31,
Wherein the spacing between the inner surface of each elongated barrel and the outer surface of the crossstring included by the last elongated barrel is in the range of about 0.64 mm to 0.69 mm. 20. The method of claim 19,
Wherein at least twenty two grommets having the elongated barrel are disposed on the crossstring. 20. The method of claim 19,
Wherein for each crossstroke in which the grommet having the stretched barrel is disposed, a second grommet having an elongated barrel is disposed at an opposite intersection of the string bed boundary and the crossstring. 20. The method of claim 19,
Wherein each of the stretched barrels is integrally formed on one of the first and second grommet strip segments. 20. The method of claim 19,
Wherein each grommet having said elongated barrel is made of a material essentially consisting of a polyether having an amide blocker. 20. The method of claim 19,
Characterized in that each grommet having said elongated barrel is made of a material essentially consisting of polyamide.

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