EP2716333B1 - Badminton racket - Google Patents

Description

The invention relates to a badminton racket.

In the field of racket sports, especially for badminton, the flexibility of a rod makes it possible to confer some power on a racket, that is to say to allow it to impact a steering wheel to transmit kinetic energy relatively important. In contrast, the rigidity of a rod allows a precise strike, especially when finalizing a shot.

Known snowshoes use both the flexibility and stiffness of a connecting rod between their handle and frame to attempt to achieve relatively high power and accuracy. This compromise approach is not entirely satisfactory, as neither power nor accuracy is optimized.

Some snowshoes use elongated oval section stems in a direction parallel to the racquet's sieve plane. This geometry is supposed to improve the stability of the racket in torsion but tends to decrease its rigidity in flexion in a direction perpendicular to the screen, that is to say in the direction along which the sieve strikes the steering wheel. This induces a lack of accuracy of the racket.

It is these drawbacks that the invention intends to remedy more particularly by proposing a new racket which makes it possible to obtain improved power and typing accuracy compared with rackets of the state of the art.

For this purpose, the invention relates to a badminton racket which comprises a frame, a handle and a rod connecting this frame to this handle, the rod having, in cross section, a circular outer shape. This racket defines a first direction parallel to a longitudinal axis of the rod, a second direction perpendicular to the first direction and parallel to a plane according to which extends a sieve mounted in the frame and a third direction perpendicular to the first and second directions and in the plane of the sieve. According to the invention, the rod has a flexural rigidity in the third direction which is greater than its bending stiffness in the second direction. The stem is hollow and has a wall thickness in the third direction greater than its wall thickness in the second direction. A central hollow volume of the rod has, in cross section, an elongate contour, with its largest dimension parallel to the second direction.

WO 2010/041362 A1 discloses a badminton racket according to the preamble of claim 1.

US 2003/0144071 A1 discloses a tubular element that can be integrated with a badminton racket. This tubular element has, in section, a different bending stiffness in two perpendicular directions. However, these two directions are not defined with respect to the structural elements of a badminton racket.

Thanks to the invention, the differentiated flexural rigidity of the rod, in the second direction and in the third direction allows, when the user arms his blow, to bend the rod, elastically, and to store the rod. energy in the rod in the second direction. This energy is transmitted to the wheel when the shot is made by moving the racquet overall in the third direction. The power of the racket is improved by the relatively low stiffness of the rod in flexion in the second direction. The accuracy of the racket is not degraded because the bending stiffness in the third direction is relatively high.

• Le matériau constitutif de la tige est homogène autour de l'axe longitudinal de la tige.
• La tige est équipée de moyens de renfort localisé de sa rigidité en flexion selon la troisième direction.
• Les moyens de renfort sont alignés selon la troisième direction.
• Les moyens de renfort sont apposés sur l'extérieur ou l'intérieur de la tige.
• Les moyens de renfort sont formés par des bandes contenant des fibres de carbone.

According to advantageous but non-compulsory aspects of the invention, a racket according to the invention may incorporate one or more of the following features taken in any technically permissible combination:

• The constituent material of the rod is homogeneous around the longitudinal axis of the rod.
• The rod is equipped with local reinforcement means of its flexural rigidity in the third direction.
• The reinforcement means are aligned in the third direction.
• The reinforcement means are affixed to the outside or the inside of the rod.
• The reinforcement means are formed by strips containing carbon fibers.

• la figure 1 est une vue en perspective d'une raquette conforme à un premier mode de réalisation de l'invention ;
• la figure 2 est une section à plus grande échelle selon la ligne II-II à la figure 1 ;
• la figure 3 est une section analogue à la figure 2, pour une raquette conforme à un exemple utile à la compréhension de l'invention et
• la figure 4 est une section analogue à la figure 2, pour une raquette conforme à un autre exemple utile à la compréhension de l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of three embodiments of a racket in accordance with its principle, given solely as an example and made with reference to the accompanying drawings in which:

• the figure 1 is a perspective view of a racket according to a first embodiment of the invention;
• the figure 2 is a larger-scale section along the line II-II to the figure 1 ;
• the figure 3 is a section similar to the figure 2 , for a racket according to an example useful for understanding the invention and
• the figure 4 is a section similar to the figure 2 , for a racket according to another example useful for understanding the invention.

The racket 1 shown in figures 1 and 2 comprises a frame 2 in the form of a closed loop and a handle 4 intended to be taken in hand by a user. A rod 6 connects the handle 4 to the frame 2 and extends along a longitudinal axis X ₁ which constitutes a longitudinal axis of the racket 1. A sieve 8 is mounted in the frame 2. This sieve 8 is formed of longitudinal ropes 82 which extend parallel to the axis X ₁ and the transverse ropes 84 which extend perpendicularly to this axis. The ropes 82 and 84 pass through eyelets 22 disposed in orifices 24 which pass through the frame 2 from one side to the other, from its outer surface to its inner surface.

Note P ₈ the plane of the sieve 8, that is to say a plane containing both the ropes 82 and 84.

X ₂ denotes an axis contained in the plane P ₈ perpendicular to the axis X ₁ and passing through the geometric center C ₈ of the sieve 8. The axis X ₂ is a transverse axis for the racket 1.

In addition, X ₃ denotes an axis perpendicular to the plane P ₈ , thus to the axes X ₁ and X ₂ and passing through the center C ₈ . For the sake of clarity, the X axis ₃ is represented at figure 1 only on the geometric mark drawn next to the racket. It can be called a frontal axis, in the sense that it defines the normal strike direction of the racket 1.

D ₁ denotes respectively a direction parallel to the axis X ₁ and from the handle 4 to the frame 2, D ₂ a direction parallel to the axis X ₂ and going from the left to the right to the figure 1 and D ₃ a direction parallel to the axis X ₃ and going from the top down to the figure 1 . The direction D ₂ is a lateral direction for the racket 1, while the direction D ₃ is a frontal direction.

As is more particularly apparent from the figure 2 , the rod 6 comprises an outer radial surface 62 circular and centered on the axis X ₁ . The circular nature of the surface 62 gives a satisfactory aesthetic appearance to the racket 1, regardless of the viewing angle.

The rod 6 is hollow and V ₆ is noted its interior volume which is oval section, with its largest dimension aligned on the axis X ₂ .

The constituent material of the rod 6 comprises a polymer resin in which reinforcement fibers, for example carbon, are embedded. This material is homogeneous around the axis X ₁ .

The rod 6 is tubular and its thickness varies around the axis X ₁ . More specifically, given the geometry of the surface 62 and the volume V ₆ , the wall thickness e ₂ of the rod 6 in the direction D ₂ is smaller than the thickness e ₃ of the wall of this rod in the direction D ₃ . Thus, the rod 6 has a flexural stiffness differentiated according the directions D ₂ and D ₃ . More specifically, considering that the rod 6 is embedded in the handle 4, a bending movement of the rod 6 in the direction D ₂ can be considered as a rotational movement about an axis X ' ₃ parallel to the axis X ₃ and passing through the point of embedding of the rod 6 in the handle 4. Similarly, a bending movement in the direction D ₃ can be considered as a rotation about an axis X ' ₂ parallel to the axis X ₂ and passing through a point of embedding of the rod 6 in the handle 4.

Given the geometry in section of the rod 6, it is more flexible in the direction D ₂ than in the direction D ₃ .

When a user arms his shot, he moves the racket 1 in a direction of advance, while the plane P ₈ is generally parallel to this direction in advance. Under these conditions, given the relatively high flexibility of the rod 6 in the direction D ₂ , the rod 6 flexes elastically and stores energy. When he is about to hit the steering wheel, the user turns the racket about a quarter turn around the axis X1, which has the effect of bringing the direction D ₃ in the direction of movement of the racket 1. In these conditions, when the racket hits the steering wheel, it is relatively rigid, that is to say stiffer than in the direction D ₂ . It follows that even if the rod 6 restores the energy stored elastically during the first part of the movement, the accuracy of the shot is good, since the racket is quite rigid in the direction D ₃ .

This differentiated behavior of the rod 6 in flexion along the directions D ₂ and D ₃ results from the difference between the thicknesses e ₂ and e ₃ .

In the examples useful for the understanding of the invention represented in figures 3 and 4 elements similar to those of the first embodiment bear the same references. In what follows, only what distinguishes these embodiments from the first is described.

In the example of the figure 3 , the outer radial surface 62 of the rod 6 is non-circular section, in this case oval, with its largest dimension oriented in the direction D ₃ The volume V ₆ is, in turn, circular section. Thus, the wall thickness e ₂ of the rod 6 in the direction D ₂ is smaller than the wall thickness e ₃ in the direction D ₃ .

In the example of the figure 4 , the outer radial surface 62 of the rod 6 is circular in section as is the volume V ₆ . Two reinforcements 64 are integrated in the rod 6 and extend in the vicinity of the surface 62, that is to say on the outside thereof, being aligned in the direction D ₃ .

These reinforcements 64 may be made by strips containing carbon fibers, optionally impregnated with resin, with a variable carbon fiber density according to the desired difference in rigidity. Thus, the elements 64 can locally reinforce the bending stiffness of the rod 6, in the direction D ₃ since they are aligned in this direction.

In the direction D ₂ , the reinforcements 64 have little effect on the bending behavior of the rod 6 because they are subjected to displacements, and therefore to stresses less than those to which they are subjected during flexion along D ₃ .

The invention is not limited to the described embodiments. Thus, the volume D ₆ of the first embodiment may be of other than oval section, for example polygonal. Similarly, the surface 62 may be of section other than oval to the figure 3 , for example polygonal.

The orientation of the directions D ₁ , D ₂ and D ₃ along the axes X ₁ , X ₂ and X ₃ is given by way of example and can be reversed.

According to a variant not shown, the reinforcements 64 may also be affixed inside the rod.

The features of the embodiments and alternatives contemplated above may be combined with one another.

Claims (6)

1. A badminton racket (1) comprising a frame (2), a handle (4) and a hollow shaft (6) connecting the frame to the handle, the shaft (6) having a circular outer shape (62) in transverse section, said racket defining:

   - a first direction (D₁) parallel to a longitudinal axis (X₁) of the shaft,

   - a second direction (D₂) perpendicular to the first direction (D₁) and parallel to a plane (P₈) in which strings (8) extend mounted in the frame, and

   - a third direction (D₃) perpendicular to the first and second directions and the plane of the strings,

   characterized in that:

   - the bending rigidity of the shaft (6) in the third direction (D3) is greater than its bending rigidity in the second direction,

   - the wall thickness (e₃) in the third direction (D₃) is greater than its wall thickness (e₂) in the second direction (D₂),

   - a central hollow volume (V₆) of the shaft (6) has an elongated contour in transverse section, with its largest dimension parallel to the second direction (D₂).
2. The racket according to claim 1, characterized in that the component material of the shaft (6) is homogenous around the longitudinal axis (X₁) of the shaft.
3. The racket according to claim 1, characterized in that the shaft is equipped with means (64) for locally reinforcing its bending rigidity in the third direction (D₃).
4. The racket according to claim 3, characterized in that the reinforcing means (64) are aligned in the third direction (D₃).
5. The racket according to one of claims 3 and 4, characterized in that the reinforcing means (64) are fixed on the outside or inside of the shaft (6).
6. The racket according to one of claims 3 to 5, characterized in that the reinforcing means (64) are formed by bands containing carbon fibers.

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