Abstract:
A sports racket frame including a main body which has an intermediate portion in the vicinity of which is provided at least one reinforcing member which defines, with the intermediate portion, an inner volume therebetween which extends about an outer periphery of the intermediate portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a racket frame, a racket provided with such a frame, as well as to a set of a plurality of these frames. 
     The invention relates more particularly to a racket provided with a head, such as a tennis, badminton or squash racket. 
     2. Description of the Related Art 
     U.S. Pat. No. 6,012,996 discloses such a racket which comprises a frame made of a fiber-reinforced plastics material. This frame, which is composed of a head, a handle and a throat located between the head and the handle, presents an oval main body, formed by two inner tubes and an outer tube. 
     According to the teaching of this document, the two inner tubes are disposed side by side, with the result that their adjoining walls form a cross rib, intended to reinforce the frame, while the presence of the outer tube makes it possible to reduce the stresses likely to be produced at the level of this rib. 
     It is an object of the present invention to make a racket frame constituting an alternative to the prior art set forth hereinabove. 
     SUMMARY OF THE INVENTION 
     To that end, it relates to a racket frame, particularly for tennis, squash or badminton, comprising a tubular body, characterized in that the tubular body has at least one intermediate portion in the vicinity of which are provided reinforcing means, these reinforcing means defining, with this intermediate portion, an inner volume extending over the whole outer periphery of the intermediate portion. 
     The invention also has for an object a racket, particularly for tennis, squash or badminton, comprising a frame presenting a head, as well as strings stretched within and around this head, characterized in that this frame is as defined hereinabove. 
     Finally, the invention has for its object a set of frames, comprising a plurality of types of frames as defined hereinabove. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more readily understood on reading the following description given by way of non-limiting examples, with reference to the accompanying drawings, in which: 
     FIG. 1 is a view in perspective of a racket according to the invention. 
     FIG. 2 is a view in longitudinal section, partially illustrating the frame of the racket of FIG.  1 . 
     FIG. 3 is a view in transverse section along line III—III of FIG.  2 . 
     FIGS. 4 and 5 are views in transverse section, similar to FIG. 3, illustrating two variant embodiments of the invention, and 
     FIG. 6 is a view in longitudinal section, similar to FIG. 2, illustrating a third variant of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, the racket illustrated in FIG. 1, which is generally designated by reference  2 , comprises a handle  4  around which a covering tape  6 , also called a “grip”, is wound. The handle is extended by a head  8 , of oval shape, within which strings  10  are stretched. The region between the handle and the head, called the throat  12 , includes divergent branches  14 , joined by a bridge  16  at their end opposite the handle  4 . 
     The handle  4 , the head  8  and the throat  12 , which form the frame of the racket, comprise a rigid tubular body  18  illustrated in particular in FIG. 2, which is for example made of aluminium or more advantageously of composite material. This tubular body may for example be manufactured from carbon fibers which may also be mixed with other types of fibers, such as glass fibers, all these fibers being bonded in a matrix which may be a thermosetting or thermoplastic resin. An epoxide resin matrix, for example, may advantageously be used. 
     This tubular body  18  comprises a main portion  20  of substantially constant section, as well as an intermediate portion  22 , forming a neck. This latter, which is coaxial to the main portion  20 , presents a transverse dimension less than said main portion and is joined thereto via two peripheral shoulders  24 . 
     In the example described and shown, this intermediate portion  22  is present on one of the branches  14  of the throat  12 . In a variant, it may equip another region of the frame. It may also be envisaged to provide a plurality of similar intermediate portions. 
     As shown in FIG. 2, a reinforcing element  26 , of tubular shape, covers the intermediate portion  22 . To that end, this element  26  extends between those regions of the main portion  20  adjacent the shoulders  24 . 
     This element  26  is made for example of metal, plastics material or, preferably, composite material. Furthermore, it is coaxial to the main portion  20 , as well as to the intermediate portion  22 . It is rigidly fixed on the aforementioned regions of the main portion  20 . 
     This means that there is essentially no degree of freedom between the main portion  20  and the reinforcing element  26 , in particular along the principal axis A of the tubular body  18 . Such a fixation, which corresponds to a complete bond between the main portion and the reinforcing element, is effected, for example, by intimate bond of these latter during moulding thereof, or by adhesion, particularly in the case of aluminium being used. 
     The inner wall of the reinforcing element  26  thus forms, with the opposite outer wall of the intermediate portion  22 , an inner volume  28  of annular shape, extending over the whole of the periphery of this intermediate portion  22 . This volume  28  has a longitudinal dimension, or length “L”, included for example between 2 and 10 cm, and a transverse dimension, or thickness “e”, included for example between 0.5 and 5 mm. The volume is filled with a gas, which may, in particular, be air. 
     FIG. 4 illustrates a first variant embodiment of the invention, in which the mechanical elements similar to those of FIGS. 1 and 2 are attributed the same reference numbers, increased by 50. According to this variant, the tubular element  26  is replaced by a plurality of rods  76  which extend over the periphery of the intermediate portion  72 . 
     FIG. 5 illustrates a second variant embodiment of the invention in which the mechanical elements similar to those of FIGS. 1 and 2 are attributed the same reference numbers, increased by 100. According to this second variant, the tubular element  26  is replaced by a plurality of bands  126  forming arcs of circle, which extend over the outer periphery of the intermediate portion  122 . 
     FIG. 6 illustrates a third variant of the invention, in which the mechanical elements similar to those of FIGS. 1 and 2 are attributed the same reference numbers, increased by 150. 
     According to this third variant, the reinforcing element  176  is rigidly fixed, at only one of its ends, on the main portion  170 . On the other hand, it is connected to the latter, at its other end, with the interposition of a deformable ring  180 . 
     The latter allows a degree of freedom, along the principal axis A, between the main portion  170  and the reinforcing element  176 . This ring may for example be glued both to this portion  170  and to this element  176 , with the result that it is subject to a certain shear during their mutual displacement along axis A. In a variant, this ring need not be glued, but simply interposed between the portion  170  and the reinforcing element  176 , with the result that it is able to rub along the latter during their mutual displacement. 
     Furthermore, the volume  178  is filled with a foam  182  which is for example of the EVA (ethylene-vinyl-acetate) type. In a variant, such a foam may be replaced by any other material which does not substantially influence the mechanical behaviour of the whole of the racket. Such material may, inter alia, be a gel. 
     The volume, whether it be filled with a gas or a solid material, is neutral with respect to the mechanical behaviour of the racket, insofar as it does not constitute a structural element thereof. In fact, it forms a bifurcation between the intermediate portion of the main body and the reinforcing means, and contributes to separating them mechanically. This volume does not act against the functioning of the racket, particularly concerning flexion and shear. 
     In all of the examples described and shown, mention has been made of an intermediate portion, whose transverse dimension is smaller than the main portion of the tubular body. By way of variant, this intermediate portion may present a transverse dimension substantially similar to that of this main portion. In such a hypothesis, this intermediate portion is in that case surrounded by a reinforcing zone of larger diameter, which may be made in the form of a tubular element or of discrete elements, as in FIGS. 3 to  5 . 
     It is advantageous to employ reinforcing means extending over the periphery of an intermediate portion of the tubular body, belonging to the frame of the racket. In effect, these reinforcing means make it possible to increase the rigidity of the racket according to the invention. 
     In addition, the possible presence of deformable means makes it possible to modulate the rigidity given to this racket. Consequently, it may be envisaged to create a range of rackets presenting various rigidities, as a function in particular of the users&#39; needs.