EP0211738A1 - Tennis racquet - Google Patents

Abstract

Tennis racket in which the string (20) is at least partially constituted by a single string (8) which passes around rollers (16) arranged in the frame (2) and of which at least one end is subject to a tensioning device (22), arranged in the racket handle (14), characterized in that said tensioning device comprises at least one spring (24, 26) connected to said end of the rope and an adjustment device (28, 30, 32 ) to vary the tension imparted by said spring to said rope, said adjustment device comprising an operating wheel (32) rotatably mounted on the end of the racket handle and applied against this end under the force exerted by said spring, the wheel and the end of the handle having complementary anti-rotation interlocking shapes.

Description

Traditional tennis rackets have fixed strings having no flexibility other than that which results from their natural elasticity. Because the strings are fixed, the initial tension of the strings is also fixed.

Various factors influence this tension, such as the ambient temperature and humidity, or the duration and strength of the game, and, as a rule, the tension decreases while it would be desirable to keep it as constant as possible.

Better yet, we are trying to make this tension adjustable in order to allow players to adjust their play according to the opponent. In a known racket model, this tension is adjusted by means of a screw and nut device housed in the racket handle and attached to several longitudinal strings of the sieve. This arrangement has two limits: on the one hand, the tension adjustment can only concern a few longitudinal strings close to the center of the screen and, on the other hand, the tension remains liable to vary according to external factors, so that readjustment is frequently required.

Also known from document NL 22 409 is a rudimentary tensioning device using a compressed spring. It is advisable to have a tool to drive the adjustment nut and it can be seen that the adjustment range is quite narrow since the spring has practically contiguous turns. Finally, no means of locking the nut is provided, which therefore risks loosening.

The object of the present invention therefore consists of a tennis racket in which the string is at least partially constituted by a string single which passes around rollers arranged in the frame and at least one end of which is subject to a tensioning device, arranged in the racket handle, characterized in that said tensioning device comprises at least one spring connected to said end of the rope and an adjustment device for varying the tension imparted by said spring to said rope, said adjustment device comprising an operating wheel rotatably mounted at the end of the racket handle and applied against this end under the force exerted by said spring, the wheel and the end of the handle having complementary interlocking anti-rotation shapes.

• - la figure 1 est une vue de dessus d'un premier mode de réalisation d'une raquette selon la présente invention où la partie supérieure du cadre et du manche a été supprimée pour des raisons de clarté ;
• - les figures 1a et 1b sont des vues en pers­pectives détaillées illustrant les formes complémen­taires de la molette et de l'extrémité du manche ;
• - la figure 2 est une vue en coupe prise suivant la ligne II à la figure 1 ;
• - la figure 3 est une vue en perspective éclatée illustrant l'assemblage du dispositif de tensionnement et du manche ;
• - la figure 4 est une vue schématique similaire aux figures 1a, 1b illustrant une variante de formes complémentaires de la molette et du manche ;
• - la figure 5 est une vue latérale illustrant un autre mode de réalisation du manche ;
• - les figures 5a et 5b sont des coupes de la figure 5 prises suivant les lignes Va et Vb respective­ment ;
• - la figure 6 est une vue de détail illustrant une variante de réalisation des roulettes de renvoi du tamis ;
• - la figure 7 illustre schématiquement une raquette dont le tamis est constitué d'une corde "horizontale" à tensionnement fixe, et de deux cordes "verticales" à tensionnement variable ;
• - la figure 8 illustre une variante du dispositif de tensionnement où les ressorts sont à caractéristique variable ;
• - la figure 9 illustre une autre variante du dispositif de tensionnement permettant d'établir une tension initiale du ressort différente de la tension initiale du cordage ; et
• - la figure 10 illustre une variante du dispositif de tensionnement où les ressorts sont montés "en ligne".

The details and advantages of the invention will appear clearly on reading the description which follows, with reference to the appended drawings, in which:

• - Figure 1 is a top view of a first embodiment of a racket according to the present invention where the upper part of the frame and the handle has been deleted for reasons of clarity;
• - Figures 1a and 1b are detailed perspective views illustrating the complementary shapes of the wheel and the end of the handle;
• - Figure 2 is a sectional view taken along line II in Figure 1;
• - Figure 3 is an exploded perspective view illustrating the assembly of the tensioning device and the handle;
• - Figure 4 is a schematic view similar to Figures 1a, 1b illustrating a variant of complementary shapes of the wheel and the handle;
• - Figure 5 is a side view illustrating another embodiment of the handle;
• - Figures 5a and 5b are sections of the Figure 5 taken along lines Va and Vb respectively;
• - Figure 6 is a detail view illustrating an alternative embodiment of the screen return wheels;
• - Figure 7 schematically illustrates a racket whose sieve consists of a "horizontal" rope with fixed tensioning, and two "vertical" ropes with variable tensioning;
• - Figure 8 illustrates a variant of the tensioning device where the springs are of variable characteristic;
• - Figure 9 illustrates another variant of the tensioning device for establishing an initial tension of the spring different from the initial tension of the rope; and
• - Figure 10 illustrates a variant of the tensioning device where the springs are mounted "in line".

If we consider Figure 1, the racket designated as a whole by the reference 10 comprises a closed frame 12 of substantially oval shape and a handle 14 secured to the frame.

Return rollers 16 are housed in the frame around the entire periphery of the frame and a rope 18 is stretched through the frame 12 passing successively around the rollers 16 so as to constitute a conventional screen 20 formed of longitudinal sections 18l and sections cross 18t which cross successively above and below.

In this embodiment, the cord 18 is formed of a single cord, the two ends of which extend into the handle 14 and are subjected to a tensioning device 22.

The tensioning device comprises two springs 24 and 26 hooked at one end to the ends of the rope 18 and at the other end to a slider 28 which can be moved inside the handle in the longitudinal direction using a threaded rod 30 which is engaged in a tapped hole in the center of the cursor.

The threaded rod is secured, on the side of the end of the handle, to an operating wheel 32 which is held firmly applied against the end of the handle by the tension of the springs. The operating wheel has a sufficient size to be easily rotated by hand and at any time desired by the player, including during the game.

Thanks to the mounting of the rope on the idler rollers 16, any additional or decrease in tension is almost instantly distributed uniformly over the entire rope.

The wheel and the end of the handle have complementary nesting shapes intended to prevent untimely rotation of the wheel.

As illustrated in FIGS. 1a and 1b, the thumbwheel 32 has a hollow shape 34 surrounded by a crown with internal toothing 36 and the handle ends in an end piece 38, integral with the handle and having a complementary relief shape 40 surrounded by '' an external radial toothing 42.

According to various variants, the teeth 36 and 42 can be symmetrical slopes, or asymmetrical slopes so as to allow a unidirectional rotation, in the direction of increasing the tension of the springs, with reasonable effort on the part of the user, corresponding to the deformation effort of the teeth 36 and 42.

Preferably, the effort required to turn the dial in the direction of decrease of spring tension will be higher. If the tests justify it, the teeth can be made of practically non-deformable material, in which case it will be advisable to exert on the wheel first of all a traction greater than the force applied by the springs to axially separate the two teeth and allow rotation wheel in one direction and / or the other.

As illustrated in Figure 2, the rollers are arranged in recesses 44 formed in the thickness of the racket frame. Each roller proper is made of a suitable material taking into account the forces involved and has a circumferential groove 46 for receiving the rope.

These rollers have a central bore 48 engaged on an axis 50 which may, depending on the applications, have come integrally with the frame itself, the latter being advantageously made in two superposed parts and glued or welded one to the other for assembly conveniences, or else be made in the form of a separate piece, of suitable material.

FIG. 3 illustrates a practical embodiment of the handle in two superimposed semi-cylindrical shells 14a, 14b and assembled using screws 52, this allowing easy access to the tensioning device, in particular when replacing the rope of the racket.

One of the two shells of the handle has a longitudinal light 54 by which the position of the cursor 28 can be visually noted. A graduation 56 along the light 54 makes it possible to know the tension of the cord directly.

The racket which has just been described may be the subject of numerous variants, some of which will now be described. Other variants not described will appear to those skilled in the art, such as in particular the number and arrangement of the idler rollers, the specific characteristics of the springs (stiffness / elongation) or even the replacement by a single spring working for elongation or even compression.

If we first examine FIG. 4, the racket handle designated by the reference 100 and the operating wheel 102 of the tensioning device, received inside the handle and not shown for reasons of clarity, comprise both complementary radial grooves 104 distributed at a regular angular pitch a and formed by successive projections and depressions.

Thus, when the springs of the tensioning device are under tension, the grooves of the wheel come to positively engage in the grooves of the handle and prevent any accidental rotation of the wheel and a relaxation of the tension which could result therefrom. The user can however, with a reasonable effort, print with the thumbwheel a rotation, in one direction or the other, in order to vary the tension of the springs.

Advantageously, an angular pitch of the grooves will be chosen such that the rotation of the dial on one pitch modifies the tension of the springs by a quantified value. For example, jumping from one groove to the next could correspond to a variation in spring tension of 500gf. Knowing the initial tension of the string, the player can therefore know at any time the resulting tension by simply counting the number of steps of rotation of the wheel.

The assembly of the partially removable handle illustrated in FIG. 5, and in sections 5a, 5b is intended to facilitate stringing operations on the racket.

For this purpose, the handle has a part removable 110 of substantially semi-cylindrical shape, terminating at one end by a whole end piece 112 on which is fixed the thumb wheel 102 for operating the tensioning device and at the other end by a tongue 114 for semi-cylindrical interlocking.

The handle also comprises a fixed part 116 of semi-cylindrical shape also connected to one end in extension of the frame 118 of the racket, and comprising at its other end a nesting tongue 120.

Each of the fixed and removable parts of the handle has a nesting housing intended to receive the nesting tongue of the other part. As illustrated in FIGS. 5a, 5b, these interlocking housings include internal longitudinal ribs 122 forming slides for the edges of the interlocking tongues 114, 120.

The removable part 110 carries the operating wheel 102 as well as the entire tensioning device. In this way, when this part is dismantled, there is easy access to all the elements of the tensioning device for making adjustments if necessary, and for hooking the strings on the springs during the initial stringing, or a subsequent record.

Of course, this improvement is not limited to the embodiment described and shown, but extends to any embodiment in which a part of the handle is removable and mounted in telescopic interlocking on the rest of the handle and the racket, the part removable carrying all tensioning devices.

FIG. 6 illustrates an alternative embodiment of the rollers 124 distributed around the periphery of the frame 126 and around which the cord is wound 128 of the sieve between two successive crossings of the frame, in the form of semi-rollers 124.

As illustrated, a semi-roulette consists of a notched roulette presenting a cut out according to a given angular sector, here close to 90 degrees. This structure allows multiple advantages:

- There is no need to put the rollers in place before assembling the two half blanks of the frame. Indeed, the frame is firstly constituted by joining the two blanks together, by welding, gluing or any other suitable technique, then the semi-rollers are engaged in the frame through the peripheral lights arranged opposite each axis. of caster 130, then engaged on their respective axes by snap-fastening.

- The replacement of a semi-roulette is made possible, which is not the case for whole castors.

- Connection studs 132 between the two frame blanks can be provided opposite the roller axes, these studs increasing the rigidity of the frame and carrying stop fingers 134 limiting the rotation of the semi-rollers to approximately 45 degrees apart and else from their average position.

Insofar as it has been found in practice that the rotation of the rollers around their axes is limited to at most a few tens of degrees depending on the range of tensions applied to the rope, it is indeed not strictly essential to provide complete casters.

In FIG. 7, a racket is shown diagrammatically, the sieve of which comprises a 128h "horizontal" cord starting from a first stop 136 and ending at a second stop 138 and forming all horizontal crossings of the sieve. This rope is placed under a fixed tension of 20kgf for example.

The vertical rope is split into two cords, a "straight" 128VD rope starting from a stop 140 and ending at one of the springs of the tensioning device after a certain number of vertical outward and return journeys constituting the right vertical half of the sieve. ; and a 128VG "left" cord arranged substantially symmetrically from a stop 142 and ending at the other spring of the tensioning device.

It has indeed been found that in certain cases the adjustment of the tension of the "horizontal" stringing is not strictly essential and this solution represents an interesting compromise.

Preferably, in this case, horizontal and vertical ropes of different nature will be chosen, that is to say made of different materials, of different sections, etc. This is symbolized in the figure by the different representation of the two ropes. (single continuous line for horizontal rope, double continuous line + dashes for vertical line).

Provision may be made for the tensioning of the vertical strings to only concern a limited number of strings on either side of a central line, the strings located furthest to the outside being mounted under fixed tension. This option can also be used for horizontal strings. (Not shown in the figures).

In the variant of tensioning device illustrated in FIG. 8, the springs 144, 146 are compression springs with variable characteristics. The springs are interposed between the movable cursor 148 along the central threaded rod 150, and the operating wheel. The two strings 128 coming from the sieve cross the slider via two passages 152 and are then hung on cups 154 bearing on the end of the springs.

These are coil springs formed from a wire with increasing section. In this way, the turns of wire with a small section close to the support cups will have a lower stiffness than the turns of wire with a large section close to the cursor.

When the tension increases, by moving the cursor using the operating wheel, the turns of low stiffness are first of all packed in the form of contiguous turns, so that the effective stiffness of the spring varies progressively until l 'intervention of very stiff turns.

In the embodiment of FIG. 9, the tensioning device makes it possible to establish an initial tension of the springs different from the initial tension of the rope.

The threaded rod 150 secured to the handwheel 102 comprises a smooth barrel 156, in the vicinity of the handwheel, which ends in a stop collar 158, and which carries a hooking plate 160 for the springs 144, 146, the plate therefore having a fixed position bearing on the flange 158.

A threaded cylindrical sleeve 162 is screwed onto the threaded rod. This sleeve has a smooth cylindrical body 164 and two beads 166, 167 in annular projection whose purpose is to limit the travel of a slider 168 sliding along the body of the sleeve.

The springs are connected to the slider by means of fasteners, while opposite fasteners on the cursor receive the strings 128 coming from the sieve.

Thus, by imposing on the wheel 102, a given elongation of the springs is imposed, corresponding for example to a force of 45 kgf, between the slider 168 and the plate 160. The strings 128 are then fixed on their fasteners under a standard mounting tension, for example 20kfg. In static condition, the cursor 168 is therefore stressed by springs by a force of 2 × 45 = 90kgf and by the strings by a force of 2 × 20 = 40kgf; it therefore remains applied to the annular bead 166 of the sleeve 162 under a force of 50 kgf.

In dynamic condition, when a ball hits the sieve, the deformation of the rope causes an increase in the tension of the rope which is transmitted to the cursor 168.

If the increase in tension does not exceed 25kgf per rope, the rope plays on its own elasticity, without the springs intervening.

If the increase in tension exceeds 25 kgf per rope, the cursor 168 is moved along the body 164 of the sleeve 162 and the springs participate in the collection of the tension undergone by the rope.

It is of course possible to modify at any time the position of the sleeve 162 along the threaded rod 150 by rotation of the wheel 102. For example, if the sleeve is brought closer to the wheel, the cursor moves jointly with the socket and the initial tension of the rope (20kg) increases as the cursor moves. It is noted that the tension of the springs decreases correlatively. Thus, from a given displacement of the sleeve and the cursor, the tensions of the springs and of the strings are equalized and the cursor will maintain a fixed position, even if the sleeve is continued to be displaced. Preferably, springs and the other elements of the device will be calculated so that in this position, the tension of the strings is of the order of 30kgf.

This arrangement allows both to adjust the tension of the rope, while adjusting the tension from which the springs intervene in dynamic behavior.

In fact, the tests carried out so far tend to show that this embodiment is the most advantageous.

In the variant illustrated in Figure 10, the two springs 144, 146 are mounted "in line" in the handle, which reduces the overall width of the tensioning device.

Here, the whole handle is rotatably mounted on the frame of the racket 180 and forms a hollow housing 182 internally threaded which receives a cursor 148 externally threaded. The cursor has a central passage 184 crossed by one of the cords 128a which cooperates with a compression spring 144 housed between the cursor and the end of the handle, while on the other side of the cursor is attached a tension spring 146 which cooperates with the other rope 128b.

The rotation of the handle results in an axial displacement of the cursor 148 and therefore in a correlative modification of the tension or compression of the springs 146, 144 and therefore of the tension of the strings 128a, 128b.

The device therefore has a very small transverse size which allows it to be housed in small diameter handles.

Insofar as the strings are here tensioned by springs of different nature (tension / compression), it is possible to associate such a device with an arrangement as illustrated in the figure 9 (2 independent vertical ropes right / left) which will give a somewhat different behavior to the two halves right and left of the sieve, or we will ensure the tensioning of the vertical rope with one, and the horizontal rope with the other .

Of course, all these variants can be combined with one another for specific purposes, some being if necessary discarded as a function of the results actually observed on rackets tested.

Finally, it should be noted that all of the racket embodiments described here have unprecedented dynamic characteristics, thanks to the presence of tensioning springs which store a certain energy and then restore it when the ball is struck.

In addition, we expect a significant reduction in vibrations transmitted via the stick to the player's arm, which are the cause of frequent physiological disorders.

Claims (14)

1. Tennis racket in which the string (20) is at least partially constituted by a single string (8) which passes around rollers (16) arranged in the frame (2) and of which at least one end is subject to a tensioning device (22), arranged in the racket handle (14), characterized in that said tensioning device comprises at least one spring (24, 26) connected to said end of the rope and an adjustment device (28, 30, 32) to vary the tension imparted by said spring to said rope, said adjustment device comprising an operating wheel (32) rotatably mounted at the end of the racket handle and applied against this end under the force exerted by said spring, the wheel and the end of the handle having complementary interlocking shapes (34, 36; 40, 42) anti-rotation. 2. Racket according to claim 1, characterized in that said tensioning device (22) comprises a slider (28) on which is hung said spring (24, 26), and a threaded rod (30) integral with said wheel (32 ) and engaged in a tapped hole in said slider (28). 3. Racket according to claim 2, characterized in that the handle (14) of racket comprises a light (54) longitudinal for visually controlling the position of the cursor (28). 4. Tennis racket according to any one of claims 1 to 3, characterized in that the operating wheel (32) of the tensioning device and the end of the handle of the racket have regularly complementary grooves (104) radial angularly spaced. 5. Tennis racket according to any one of claims 1 to 4, characterized in that the handle of the racket comprises a removable part (112) which carries the tensioning device and its operating wheel (102), and which is mounted by telescopic fitting on the rest of the racket. 6. Tennis racket according to any one of claims 1 to 5, characterized in that the string mounting rollers are produced in the form of semi-rollers (124), that is to say rollers scalloped according to a predetermined angular sector. 7. Tennis racket according to claim 6, characterized in that said semi-rollers (124) are mounted on their axes (130) by snap-fastening. 8. Tennis racket according to either of Claims 6 and 7, characterized in that the racket frame comprises stop fingers (134) cooperating with said semi-rollers (124) and limiting their degree of rotation . 9. Tennis racket according to any one of claims 1 to 8, characterized in that the string comprises at least one horizontal string (128h) mounted at fixed tension, and at least one vertical string (129v) mounted at variable tension at using the spring tensioning device. 10. Tennis racket according to claim 9, characterized in that the horizontal (128h) and vertical (128v) strings are of different nature. 11. Tennis racket according to one of claims 9 or 10, characterized in that it comprises two vertical strings (128VD, 128VG) forming right and left sieve halves respectively. 12. Tennis racket according to any one of claims 1 to 11, characterized in that said springs are springs with variable stiffness (144, 146). 13. Tennis racket according to any one of claims 1 to 12, characterized in that the two springs are arranged in line, one of them being a tension spring (146) and the other a compression spring (144). 14. Tennis racket according to any one of claims 1 to 12, characterized in that it comprises means (166, 168) capable of establishing an initial tension of the springs different from the initial tension of the strings.

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