EP0501895A1 - Racket with longitudinal asymmetry - Google Patents

Abstract

Racket for ball game or the like (tennis, squash, badminton, etc.). <??>Its frame (6) is visually symmetrical relative to the central longitudinal plane (1) passing via the handle (3) and containing the centre of gravity of the racket, but, by virtue, for example, of the incorporation of shock-absorbing elements (9 to 11) on one side (6g) of the frame (6), it is divided into two right/left half-parts which, although of visually identical shape, in reality have different physical characteristics. <IMAGE>

Description

The present invention relates to a ball game racket or the like, such as a tennis racket, squash racket, badminton racket, etc.

Traditionally, such a racket consists of a handle, aligned in the longitudinal axis of a flat basket. This basket is composed of a frame carrying a sieve formed by the cord, intended for striking the ball. The basket is connected to the handle either directly or via two branches in the shape of a "V". The part of the frame connecting the end of the two branches of the "V" is called "bridge".

Most existing tennis rackets are symmetrical with respect to their median longitudinal axis. In play, a tennis racket is used, among other things, to make two main strokes: the "forehand" and the "backhand". During these two strokes, the overall position of the racket sieve plane at the time of impact with the ball is similar. The plane of the sieve is then practically perpendicular to the ground, as well as to the direction provided for the return of the ball, the head of the racket being slightly raised relative to the handle.

To facilitate holding the racket in this position, some manufacturers have imagined making rackets whose longitudinal axis of the sieve is slightly inclined relative to the axis of the handle. This misalignment of the frame, if it is useful in the forehand, is a little less in the backhand, and on the other hand it becomes very inconvenient to perform the "services".

Other inventors have imagined frames of very diverse shapes, as is the case with document DE-A-3731529 aiming to move the percussion center, or even documents EP-A-0351823 and DE-A-3634599.

These known rackets, which have significant asymmetries of the screen with respect to the axis of the handle, have the disadvantage of accentuating the forces of torques at the time of impact with the ball, and therefore of causing a rotation. unpleasant grip of the racket in the player's hand.

As another state of the art, document WO-A-90/14870 can also be cited, which provides arrangements able to offset the center of gravity of the racket with respect to its median longitudinal axis.

One of the aims of the invention is to modify, without shifting the center of gravity of the racket with respect to its median longitudinal axis, or more precisely with respect to the median longitudinal plane containing this axis and orthogonal to the plane of the racket, of this racket while correcting, by the structure of said racket, the discomfort caused by offset of impacts.

Another object of the invention is to improve the stability of the racket, and therefore the accuracy of the shots, in particular on "worked", "lifted" or "caught" shots. These strokes, unlike the "flat" strokes, are strongly eccentric on the racket sieve, and it is therefore important to design a racket which can compensate, by its structure, for asymmetrical use.

The invention relates for this purpose to a racket for a ball game, or the like, generally comprising a handle aligned in the longitudinal axis of a flat basket which comprises a frame carrying a sieve formed by the rope and intended for striking the ball, a longitudinal plane which is orthogonal to the surface of this sieve and which comprises the longitudinal axis of the handle as well as the center of gravity of the racket, dividing the frame into two half-parts which, all by giving the racket an almost symmetrical external appearance, in reality has different physical characteristics. By "physical characteristics" is meant here both mechanical characteristics and dynamic and / or aerodynamic characteristics.

• Figure 1 est une vue en plan d'une première forme de réalisation de cette raquette;
• Figure 2 est une vue en coupe selon II-II de Figure 1;
• Figure 3 est une vue similaire à Figure 2, c'est à dire exécutée dans le même plan de coupe de la raquette, d'une première variante de réalisation de cette même raquette;
• Figures 4 et 5 représentent, de même façon qu'en Figures 2 et 3, deux autres variantes de réalisation de cette raquette; et
• Figure 6 est une vue en plan partielle du panier d'une autre raquette réalisée selon l'invention.

In any case, the invention will be well understood, and its advantages and other characteristics will emerge during the following description of a few nonlimiting examples of the construction of such a racket with longitudinal asymmetry without real asymmetry of external appearance, with reference to the attached schematic drawing in which:

• Figure 1 is a plan view of a first embodiment of this racket;
• Figure 2 is a sectional view along II-II of Figure 1;
• Figure 3 is a view similar to Figure 2, that is to say executed in the same cutting plane of the racket, of a first alternative embodiment of the same racket;
• Figures 4 and 5 show, as in Figures 2 and 3, two other alternative embodiments of this racket; and
• Figure 6 is a partial plan view of the basket of another racket made according to the invention.

Referring first to FIG. 1, it is a tennis racket with a completely conventional external appearance, and resembling at first glance most of the rackets currently sold by the Applicant.

• . d'un cadre rigide 6 comportant un panier (ou tête) maintenant le cordage qui forme le tamis 8 perpendiculaire au plan précité 1 et destiné à la frappe de la balle, et deux branches 4 en forme de "V";
• . puis d'une poignée 3 dont l'axe longitudinal est situé dans le plan de symétrie 1.

This racket, which is visually symmetrical in shape with respect to its plane of symmetry, axial and longitudinal 1 orthogonal to the plane of the racket, is therefore composed:

• . a rigid frame 6 comprising a basket (or head) holding the cord which forms the screen 8 perpendicular to the above-mentioned plane 1 and intended for striking the ball, and two branches 4 in the form of a "V";
• . then a handle 3 whose longitudinal axis is located in the plane of symmetry 1.

Note that the assembly formed by the handle 3 and the arms 4 is also called the "handle" 2 of the racket.

According to the invention, it is planned to manufacture a racket of external appearance practically identical to that of the racket drawn in FIG. 1, therefore of practically symmetrical shape, but which, without lateral offset of the center of gravity of the racket relative to at its median longitudinal plane 1 (as is the case for the aforementioned document WO-A-90/14870 which describes rackets having such an offset), is such that the right halves 6d and left 6g of the profile of the basket are physical characteristics (mechanical and / or dynamic and / or different).

• . En faisant varier les conditions de propagation des vibrations:
  • Soit, selon Figures 1 et 2, en intégrant, dans un seul 6g des demi-cadres, des dispositifs internes d'amortissement 9, 10, 11, tel que du matériau viscoélastique par exemple, et en réalisant la raquette avec une répartition de fibres telle que ces deux demi-cadres 6g et 6d soient de masses identiques. Dans le même esprit, il est aussi possible d'introduire de même des éléments amortisseurs différents en quantités et/ou répartitions à la fois dans ces deux demi-cadres.
  • Soit, selon Figure 3, en utilisant des composants constitutifs de chacun des demi-cadres de caractéristiques d'amortissement différentes: par exemple, comme il est symboliquement illustre par des hachures différentes sur cette figure 3, un noyau en bois d'un côté, 6g par exemple, et un noyau en Polyuréthanne de l'autre 6d, tout en ayant des masses totales identiques pour chacune de ces deux moitiés 6g et 6d.
• . En faisant varier les répartitions de masses dans chacun des demi-cadres pour en déplacer les centres de gravité respectifs tout en maintenant le centre de gravité de la raquette dans le plan longitudinal médian (1) orthogonal au plan de cette raquette. Par exemple:
  • Soit en utilisant des matériaux en quantités ou en densités différentes dans chacun des deux demi-cadres: plus de tissu de verre imprégné de résine d'un côté que de l'autre.
  • Soit en utilisant des matériaux de natures différentes dans chacun des deux demi-cadres: fibre de verre d'un côté et fibre de polyéthylène de l'autre côté.
• . En faisant varier les raideurs:
  • Soit en utilisant des matériaux différents dans chacun des deux demi-cadres: du verre d'un côté et du Carbone de l'autre par exemple.
  • Soit en utilisant les mêmes matériaux, mais en faisant varier leurs caractéristiques de souplesse par modification de l'orientation des fibres: par exemple à 30° d'un côté et à 45° de l'autre.
  • Soit en utilisant les mêmes matériaux, mais en quantités différentes: plus de renfort-verre d'un côté que de l'autre par exemple.
  • Soit en modifiant les formes des sections respectives droite-gauche.
    Selon Figure 4, où les rapports dimentionnels ont été volontairement exagérés pour la clarté de l'exposé, on voit que cette dissymétrie droite-gauche peut être engendrée par des sections du cadre légèrement différentes sur la moitié 6d et sur la moitié 6g, sans que cette différence de sections puisse être vraiment considérée comme engendrant une véritable asymétrie visuelle de forme pour la raquette.
• . En faisant varier les caractéristiques d'aérodynamisme par des formes de sections différentes d'un côté par rapport à l'autre. Selon Figure 5, cette dissymétrie droite-gauche est due à des coefficients d'aérodynamisme différents sur la moitié 6d et sur la moitié 6g: cette différence est ici due au fait que, les sections étant triangulaires et identiques en surface, les triangles correspondants sont orientés différemment sur la partie droite et sur la partie gauche, ce qui, à l'instar de la réalisation selon Figure 4, n'entraine pas de réelle dissymétrie visuelle de forme pour cette raquette.

This difference in characteristics between the two half-frames 6d, 6g can be obtained in several ways:

• . By varying the conditions of propagation of vibrations:
  • Or, according to Figures 1 and 2, by integrating, in a single 6g of the half-frames, internal damping devices 9, 10, 11, such as viscoelastic material for example, and by making the racket with a distribution of fibers such that these two half-frames 6g and 6d are of identical masses. In the same spirit, it is also possible to introduce in the same way different damping elements in quantities and / or distributions at the same time in these two half-frames.
  • Or, according to Figure 3, using constituent components of each of the half-frames with different damping characteristics: for example, as is symbolically illustrated by different hatching in this Figure 3, a wooden core on one side, 6g for example, and a Polyurethane core of the other 6d, while having identical total masses for each of these two halves 6g and 6d.
• . By varying the mass distributions in each of the half-frames to move the respective centers of gravity while maintaining the center of gravity of the racket in the median longitudinal plane (1) orthogonal to the plane of this racket. For example:
  • Either by using materials in different quantities or densities in each of the two half-frames: more glass cloth impregnated with resin on one side than on the other.
  • Or by using materials of different natures in each of the two half-frames: fiberglass on one side and polyethylene fiber on the other side.
• . By varying the stiffness:
  • Or by using different materials in each of the two half-frames: glass on one side and Carbon on the other for example.
  • Either by using the same materials, but by varying their flexibility characteristics by modifying the orientation of the fibers: for example at 30 ° on one side and at 45 ° on the other.
  • Either using the same materials, but in different quantities: more glass reinforcement on one side than on the other for example.
  • Or by modifying the shapes of the respective right-left sections.
    According to Figure 4, where the dimensional relationships have been deliberately exaggerated for the sake of clarity, we see that this right-left asymmetry can be generated by slightly different sections of the frame on half 6d and on half 6g, without this difference in sections can really be considered as creating a real visual asymmetry of shape for the racket.
• . By varying the aerodynamic characteristics by shapes of different sections on one side compared to the other. According to Figure 5, this right-left asymmetry is due to different aerodynamic coefficients on the half 6d and on the half 6g: this difference is here due to the fact that, the sections being triangular and identical on the surface, the corresponding triangles are oriented differently on the right part and on the left part, which, like the embodiment according to Figure 4, does not cause any real visual asymmetry of shape for this racket.

Finally, this difference in physical characteristics can also be obtained, according to Figure 6, by the addition of one side of the screen, for example on the left side as shown, of an element offering a wind resistance: in this case, it it is a piece of fabric 12 which is attached, for example by gluing, on the left part of the sieve.

It goes without saying that the invention is in no way limited to the exemplary embodiments which have just been described, and many other variants are possible, provided that they give the racket the asymmetry of physical characteristics straight desired left without creating real aspect dyssimetry as would be the case for example by adding elements additional (weights, damping elements, ...) on the outside of the frame 6.

Claims (10)

1 - Racket for ball game, or the like, this racket comprising a handle (2) aligned in the longitudinal axis of a flat basket, the latter comprising a frame (6) carrying a screen (8) which is formed by the string and which is intended for striking the ball, a longitudinal plane (1), orthogonal to the surface of this sieve and comprising the longitudinal axis of the handle as well as the center of gravity of the racket, dividing the frame into two half parts (6d, 6g),
characterized in that, in order to obtain a longitudinal asymmetry without shifting the center of gravity of the racket with respect to this longitudinal plane (1), this longitudinal plane of symmetry (1) divides the racket into two half-parts, right-left (6d, 6g) which, while giving this racket an almost symmetrical external appearance, actually have different physical (i.e. mechanical and / or dynamic and / or aerodynamic) characteristics. 2 - Racket according to claim 1, characterized in that these two half-parts have different stiffness characteristics. 3 - Racket according to claim 2, characterized in that this difference in stiffness is obtained by distributions or orientations of different fibers. 4 - Racket according to claim 2, characterized in that this difference in stiffness is obtained by the use of identical materials, but in different quantities. 5 - Racket according to claim 1, characterized in that these two half-parts have different damping characteristics, obtained for example, without modification of the external shape of the racket, by adding internal damping elements (9,10 , 11) inside one (6g) and / or the other (6d) of the half-parts of the frame (6) or by using constituent components of each of these half-parts having characteristics of different amortization. 6 - Racket according to claim 1, characterized in that this right-left asymmetry is created by different section shapes of the frame for points symmetrical with respect to said longitudinal plane of symmetry (1). 7 - Racket according to claim 1, characterized in that this right-left asymmetry is created by different aerodynamic coefficients. 8 - Racket according to claim 1, characterized in that these two half-parts are arranged (12) to offer a different wind resistance. 9 - Racket according to claim 1, characterized in that this right-left asymmetry is created by mass distributions which are different, while maintaining the center of gravity of the racket in said median longitudinal plane (1). 10 - Racket according to one of claims 1 to 9, characterized in that at least one of its right-left halves of frame (6d, 6g) is provided with a screen printing, decoration, or coloring, which distinguishes it from the other half.

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