Patent Application
20230051137
This patent application claims the benefit under 35 U.S.C. 119 to German Utility Model Application No. DE 10 2021 004 130.5, filed on Aug. 11, 2021, the entirety of which is incorporated herein by reference.
The present invention relates to a ball game racket frame, in particular a tennis racket frame, with improved torsional behavior.
Nowadays, ball game racket frames are highly complex high-tech structures that have to meet a number of—sometimes contradictory—requirements. In particular, ball game racket frames should allow a high power transfer to the ball and as much control as possible, while at the same time provide excellent damping properties. Furthermore, experienced players increasingly want that a ball game racket frame provides tactile feedback about the hitting behavior back to the player's hand.
In the case of all these aspects, the racket throat is of utmost importance, as it transfers the forces from the racket handle to the racket head and vice versa, and at the same time represents a central element in damping. For this reason, various throat geometries have already been proposed in the past (cf., e.g., EP 0 477 533131, EP 0 317 711 A2, EP 0 671 186 A1, DE 10 2006 004 863 B4, U.S. Pat. Nos. 5,183,265 and 5,299,801), which, however, are not optimal, in particular with respect to the aforementioned feedback.
Therefore, an object to be achieved by the present invention consists in providing an improved ball game racket frame. This object is achieved by a ball game racket frame according to any one of claims 1 and 10. Preferred embodiments of the ball game racket frame according to the invention are described in the dependent claims.
Accordingly, the present invention is directed to a ball game racket frame, in particular a tennis racket frame, comprising a head portion, a handle portion and a throat connecting the head portion to the handle portion and comprising two throat beams. The two throat beams of the throat together with the bridge of the head portion form the so-called racket heart. Each of the throat beams merges into the handle portion of the ball game racket frame at a respective first transition cross-section. Furthermore, each of the two throat beams merges into the head portion of the ball game racket frame at a respective second transition cross-section. At a distance of 10 mm from the respective first transition cross-section, each of the throat beams has a first cross-sectional profile having a first frame width (measured within the string bed plane) and a first frame height (measured perpendicularly to the string bed plane). Furthermore, at a distance of 10 mm from the respective second transition cross-section, each of the throat beams has a second cross-sectional profile having a second frame width and a second frame height. According to a first aspect of the present invention, the ratio of the second frame width to the first frame width is to be at least 1.15 and the longitudinal extension of the throat is to be at least 105 mm.
In other words, the present invention is based on tapering the width of the throat beams starting from the head portion of the ball game racket frame towards the handle portion and providing at the same time a certain minimum inner length of the throat. This has the advantage that, when the racket is subjected to a bending stress, torsion of the throat beams is achieved as close as possible to the handle portion. Better damping can be achieved by this torsion than by just bending the throat, and the torsion near the handle portion allows the player to get a better feel for the deformation of the frame and thus get an improved feedback of the ball-racket interaction. In order that sufficient torsion can occur at all, it is necessary that the throat has a certain minimum length, since with a short throat the two throat beams are stabilized too much by the bridge.
This combination of features and the advantages achieved therewith have not been considered in the prior art so far. EP 0 317 711 A2 and U.S. Pat. No. 5,183,265, for example, primarily deal with a variation of the frame height, which, however, reduces the bending stiffness over the entire racket and does not lead to the desired torsion of the throat. EP 0 671 186 A1 and U.S. Pat. No. 5,299,801 describe a tapering of the throat beam width, but in each case the length of the throat is much too short to achieve the desired effect. This also applies to DE 10 2006 004 863 B4, where the extremely dimensioned throat at the transition to the head area also prevents corresponding torsion.
In the context of the present invention, the longitudinal extension of the throat means the inner length of the throat measured (along the longitudinal axis of the ball racket frame) from the lowest point of the inner region of the throat (or heart) at the handle portion to the lower edge of the bridge.
Preferably, the ratio of the second frame width to the first frame width is at least 1.20, more preferably at least 1.25, and particularly preferably at least 1.30.
Preferably, the longitudinal extension of the throat is at least 110 mm, more preferably at least 115 mm, even more preferably at least 120 mm, and particularly preferably at least 125 mm.
Preferably, the first frame width is at most 13.0 mm, more preferably at most 12.5 mm, even more preferably at most 12.0 mm, even more preferably at most 11.5 mm, even more preferably at most 11.0 mm, and particularly preferably at most 10.5 mm.
The ratio of the second frame height to the first frame height is preferably at most 1.25, more preferably at most 1.20, even more preferably at most 1.15, and particularly preferably at most 1.10.
It is further preferred that the second frame width is at most 20.0 mm, preferably at most 18.0 mm, more preferably at most 17.0 mm, even more preferably at most 16.0 mm, even more preferably at most 15.0 mm, and particularly preferably at most 14.0 mm.
According to a further aspect, the present invention is directed to a ball game racket frame, in particular a tennis racket frame, comprising a head portion, a handle portion, and a throat connecting the head portion to the handle portion and comprising two throat beams, each of the throat beams merging into the handle portion at a respective first transition cross-section and merging into the head portion at a respective second transition cross-section. At a distance of 10 mm from the respective first transition cross-section, each of the throat beams has a first cross-sectional profile having a first frame width (measured within the string bed plane) and a first frame height (measured perpendicularly to the string bed plane). Furthermore, at a distance of 10 mm from the respective second transition cross-section, each of the throat beams has a second cross-sectional profile having a second frame width and a second frame height. The ratio of the second frame width to the first frame width is at least 1.10 and the first frame width is at most 12.5 mm.
The invention of this second aspect of the invention is based on a similar basic concept as that of the first aspect of the invention, since again the frame width of the throat beams is intended to taper from the head portion of the ball game racket frame towards the handle portion. However, in the case of this aspect of the invention, the desired torsion is not ensured by the minimum length of the throat, but by the maximum frame width of the throat beams near the handle portion. Otherwise, the above statements regarding the first aspect of the invention analogously apply to this second aspect of the invention.
Preferably, the first frame width is at most 12.0 mm, more preferably at most 11.5 mm, even more preferably at most 11.0 mm, and particularly preferably at most 10.5 mm.
Preferably, the longitudinal extension of the throat is at least 100 mm, more preferably at least 105 mm, even more preferably at least 110 mm, even more preferably at least 115 mm, and particularly preferably at least 120 mm.
Preferably, the ratio of the second frame width to the first frame width is at least 1.15, more preferably at least 1.20, even more preferably at least 1.25, and particularly preferably at least 1.30.
Preferably, the ratio of the second frame height to the first frame height is at most 1.25, more preferably at most 1.20, even more preferably at most 1.15, and particularly preferably at most 1.10.
Preferably, the second frame width is at most 20.0 mm, more preferably at most 18.0 mm, even more preferably at most 17.0 mm, even more preferably at most 16.0 mm, even more preferably at most 15.0 mm, and particularly preferably at most 14.0 mm.
In the case of both of the aforementioned aspects of the invention, it is preferred that the first frame height is at most 26.0 mm, preferably at most 25.0 mm, more preferably at most 24.0 mm, even more preferably at most 23.0 mm, even more preferably at most 22.5 mm, and particularly preferably at most 22.0 mm.
In the case of both of the aforementioned aspects of the invention, it is preferred that the second frame height is at most 25.0 mm, preferably at most 24.5 mm, more preferably at most 24.0 mm, and particularly preferably at most 23.5 mm.
In the following, a preferred embodiment of the ball game racket frame according to the invention is described in more detail with reference to the Figures, in which:
Each of the throat beams 4 merges into the handle portion 2 at a respective first transition cross-section 5 and merges into the head portion 1 at a respective second transition cross-section 6. According to the invention, the first transition cross-section 5 is defined such that it touches or is tangent to the lowest point of the inner region 10 formed by the throat 3. In other words, the first transition cross-section 5 is the cross-section which is displaced furthest from the handle portion 2 towards the head portion 1 and extends perpendicularly to the longitudinal axis of the racket and has no opening resulting from the inner region 10. Analogously, the second transition cross-section 6 is defined according to the invention such that it just touches or is tangent to the upper, outer edge 12 of the inner region 10. In other words, the second transition cross-section 6 is the cross-section that can be displaced furthest from the head portion 1 towards the handle portion 2 so that it does not contain any opening resulting from the inner region 10 and extends perpendicularly to the contour of the corresponding throat beam 4.
According to the invention, each of the throat beams 4 has a first cross-sectional profile 7 with a first frame width A and a first frame height at a distance of 10 mm from the respective first transition cross-section 5 and a second cross-sectional profile 8 with a second frame width B and a second frame height at a distance of 10 mm from the respective second transition cross-section 6. The distance is determined in each case, as shown in
According to a first aspect of the invention, the longitudinal extension C of the throat 3 is furthermore intended to be at least 105 mm. The longitudinal extension C of the throat 3 denotes the inner length of the throat, which, as shown in
The first frame height (hereinafter also referred to as D) as well as the second frame height (hereinafter also referred to as E), which are not shown in
The applicant has measured a preferred embodiment of the ball game racket according to the invention, which is to be launched on the market under the model name “Boom MP” in the year 2022. The corresponding values for the first frame width A, the second frame width B, the first frame height D, the second frame height E and the longitudinal extension C of the throat as well as the ratios B/A and E/D are revealed in the table according to
Each of the ball racket frames was unstrung during the measurement, and the grommet strip in the heart bridge was dismantled for the measurement of the longitudinal expansion of the throat.
As revealed by the table in
Only the “Ghost” model from the supplier Donnay exhibits a comparable ratio of 1.38 (cf. also the corresponding applications EP 0 671 186 A1 and U.S. Pat. No. 5,299,801). However, this prior art model has a significantly shorter longitudinal extension of the throat of only 94 mm and a significantly larger frame width A of 12.86 mm. Therefore, this ball game racket frame does not exhibit the desired torsional properties because all in all the racket heart of this ball game racket frame is too stiff.
Furthermore, there were two models from Head (“Airflow 1” and “Airflow 3”) which exhibited a significantly larger B/A ratio of 1.73 and 1.61 respectively (see also DE 10 2006 004 863 B4). However, these models had extremely dimensioned throats with first frame widths and heights at the transition to the handle of around 14 mm and around 26 mm, respectively, which also prevented the desired torsion.
During initial tests with a prototype, test players reported that the “Boom™” model ball racket frame gave them a very good feel for the deformation of the frame, which they said gave them better control over their own game.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 004 130.5 | Aug 2021 | DE | national |
