EP0106850A1

EP0106850A1 - Tennis or squash racket.

Info

Publication number: EP0106850A1
Application number: EP83900929A
Authority: EP
Inventors: Herwig Fischer
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-03-30
Filing date: 1983-03-29
Publication date: 1984-05-02
Also published as: DK545683A; EP0106850B1; JPH05589B2; DK545683D0; DK157530C; JPS59500628A; WO1983003358A1; DK157530B; US4754968A; US4595201A; DE3364342D1

Abstract

Dans une raquette de tennis ou de squash les cordes (22, 24) sont montées sans frottement sur le cadre (12) et disposées sur la surface du cadre de façon que deux brins parallèles (22c, 22d) de la même corde soient distants d'au moins un diamètre de balle. Entre ces deux brins parallèles sont disposés deux autres brins (24d) qui appartiennent à une autre corde (24). Cette disposition des cordes permet de distribuer la tension consécutive à un coup sur la balle dans des zones qui n'ont pas été en contact avec celle-ci.In a tennis or squash racket the strings (22, 24) are mounted without friction on the frame (12) and arranged on the surface of the frame so that two parallel strands (22c, 22d) of the same string are spaced d '' at least one bale diameter. Between these two parallel strands are arranged two other strands (24d) which belong to another rope (24). This arrangement of the cords makes it possible to distribute the tension following a blow on the ball in areas which have not been in contact with it.

Description

TENNIS OR SQUASH RACKETS

DESCRIPTION

_**

Technical field

5 The invention relates to a tennis or squash racket with an essentially elliptical frame, a handle connected to it and a string attached to one another within the frame, consisting of strings crossing one another, which have at least one low-friction deflected and tensioned several times in the frame with im include essential parallel string sections.

State of the art

15 In conventional tennis rackets, the strings are guided over the frame surface with a uniform or slightly differentiated tension and fixed at their ends in the frame. Because a large number of parameters go into the playing behavior of a tennis racket, the

In some cases with such opposing characteristics, it is possible with such a covering to bestow the stringing at the ideal point of impact of the ball, the "sweet spot", with favorable tension and impact loss properties. When optimizing the "Sweet

25 Spot ", a simultaneous optimization of other areas of the covering is generally not possible. This leads to balls that do not hit the" Sweet Spot "exactly

** are relatively difficult to control and that

Strain the wrist of the player. s 30

From GB-PS 380 915 a tennis racket is known in which the strings are guided over deflection rollers mounted in the frame and a number of tensioning devices for individual tensioning of individual strings are provided on the frame. This solution enables in some ways - 1 -

Measurements of fine adjustments to the tension behavior of the strings, however, are still tied to essential parameters which impair optimal tension distribution, such as in particular the stretchable string length and the course of the string.

FR-PS 784 057 describes a tennis racket in which a continuous, endless string is also guided over rollers in the frame and in the transition area between the handle and the frame, which is referred to as the heart of the tennis racket, is connected to a chip device, the one Allowing the player to change the total tension. Apart from the fact that this solution does not allow individual selection of the tension of individual strings and the tension gradient in the racket, it has also only proven to be of limited functionality, since the considerable friction occurring at the crossing points of the strings leads to the tensioning device ^¬ brought pre-tension only in a very slow creep process distributed over the entire string.

Similar solutions with deflection rollers in the frame and a tensioning device in the handle are shown in GB-PS 2 029 241 and US-PS 4 057 249. These constructions are also opposed to the concerns previously expressed.

Presentation of the invention

The invention has for its object to improve the elastic properties of the strings in particular in a non-central ball contact.

This object is achieved according to the invention in that at least in part of the stringing the immediately adjacent parallel string sections belong to different strings and that the distance between them is the same String-belonging string sections is at least about a ball radius.

With this type of string guide, the stretching of the string sections directly involved in the ball contact leads to an increased tension in those sections of the same string which run in the region of the edges of the ball contact zone. This results in a tension distribution which is characterized by high elasticity in the ball contact zone, while the stringing in an area surrounding this zone is more tensioned and is correspondingly less deflected, so that the ball during the stroke receives improved leadership. While conventional racquets the location of the "sweet spot" a is set once and for all forms at the proper racket erfindungs¬ to some ^'the meaning of the "sweet spot" in each case at the point of ball contact.

The strings are preferably at least partially extended beyond the frame area, and the string sections extending beyond the frame area are freely stretchable and connected to the string sections located in the frame area via a low-friction deflection. The strings are preferably extended into the hollow handle and, if necessary, to the bottom thereof.

This solution offers the possibility of extending the stretchable length of individual or all strings, which is of course essential for the elasticity behavior, in any way.

The advantage of this extension is particularly evident in the example of the relatively short strings located in the edge region of the frame, the tension behavior of which is always unsatisfactory in conventional rackets. correspond

There are, however, advantages for the entire sowing.

The elongated strings are preferably fastened within the handle in arbitrarily selectable longitudinal positions of an elongated slide which can be moved longitudinally in the handle and which can be moved with the aid of a tensioning device. This tensioning device offers the user the possibility of raising and lowering the total tension of the tennis racket optimized with regard to the tension distribution. It is entirely possible and even intended under certain circumstances that the tensioning process produces differently strong effects in accordance with the different string lengths.

In conventional tennis rackets, the frame is usually designed such that it is capable of absorbing shock losses within certain limits. According to the invention, shock losses, which occur in particular in the case of non-central ball contacts, can be absorbed by suspending the slider as such in an elastically or elastically damped manner.

In a further preferred embodiment of the invention, the deflection between the string section lying within the frame and the string section extending beyond the frame is in the pulling direction into the interior of the frame surface, that is to say when a string is deflected upon impact, with little friction, in the opposite direction against it braked. This enables a high reduction of impact losses, since the ball is absorbed softly and resiliently by the racket but is not immediately thrown back by the spring springing back immediately. Brief description of the drawings

1 shows a schematic, partially cut-away top view of an embodiment of a tennis racket according to the invention;

2 schematically illustrates the deflection of the stringing of a tennis racket according to the invention;

3 is a view of an embodiment of a slider;

3 is a partially cut-away side view from the left in FIG. 3;

Fig. Shows another embodiment of the slider;

6 and 7 illustrate the storage of the rollers in the frame;

8 to 11 illustrate further forms of deflecting the strings in the frame;

12 is a partially cut-away partial illustration of the handle of a further embodiment of a tennis racket;

13 shows a junction between two crossed strings of the tennis racket according to the invention. - έ -

Preferred exemplary embodiments of the invention

A tennis racket shown in FIG. 1 comprises a handle 10 and a frame 12. The handle is hollow and has at its free end a plate 14 closing the handle. Within the area formed by the frame 12 there is a string, denoted overall by 16, which is indicated in FIG. 1 only by a single string 22 drawn in completely and a further string 24 only partially shown. A longitudinally displaceable slide piece 18 is attached within the hollow handle 10. Through the plate 14 closing the handle, a clamping bolt 20 is freely rotatable, which enters with thread engagement in the lower end of the slider 18, so that a rotation of the clamping bolt

Longitudinal displacement of the slider 18 can be achieved within the handle 10. The individual strings of the stringing 16 extend through bores 26 arranged in longitudinal sections in the slider 18 and can thus be re-tensioned by the user together with the aid of the clamping bolt 20.

In the exemplary embodiment shown, the tennis racket has a diagonal covering. The string 22 is fixed to the frame at point A at the bottom left in FIG. 1 and extends with a first section 22a diagonally across the frame surface to a deflection roller 28. From there, the string 22 is outside the frame 12 to another Deflection roller 30 performed. A subsequent section 22b of the seat 22 runs parallel to the section 22a to a deflection roller 32 (point C). The string 22 runs from the deflection roller 32 through one of the bores 26 of the slide piece 18 within the hollow handle 10 (point D) to a further deflection roller 34. Two further mutually parallel sections 22c, 22d of the string 22 are via deflection rollers 38 guided symmetrically to the string sections 22a, 22b. The end of the string section 22d is fixed at point B on the frame 12. The distance between the parallel stretcher sections 22a and 22b or 22c and 22d corresponds approximately to the radius of a tennis ball.

The other strings of the strings 16 are essentially similar to the strings 22. The parallel string sections of the individual strings have essentially the same spacing and accommodate the string sections of other strings between them. Thus, for example, a string section 24d of a string 24 extends between the string sections 22c, 22d of the string 22, while the string section 24c, which is parallel to this, extends outside the string sections 22c, 22d.

If, for example, a ball strikes at point P during a stroke, the string sections 22a, 22c and 24d are hit directly by the ball and stretched accordingly. The tensile force occurring in these string sections is transmitted almost undiminished to the string sections 22b, 22d and 24c by the deflecting rollers, so that there is an increased tension in an annular area around the point P. The resulting deflection of the strings 16 is shown schematically in FIG. 2. While the strings are curved concavely to the ball in the usual way directly in the area of the ball contact zone, a convex curvature can be seen in the adjacent sections F of the strings due to the increased tension. The ball 42 is therefore received in a relatively narrow trough, which gives the ball guidance and ensures that the ball 42 essentially rests in a direction perpendicular to that when the insemination springs back

Level E of the frame surface is accelerated.

OMPI - δ -

In order to reduce the friction in the nodes at which the individual string sections intersect, the parallel groups of string sections are represented in FIG. 1 on the one hand by the string sections 22a, 22b and on the other hand by the string sections 22c, 22d, 24c and 24d , arranged in two different levels. The strings are therefore not networked with each other, but run freely past each other. On the other hand, in order to avoid an undesirable distortion of the strings when the ball hits, these are

String sections are connected to each other at the crossing points by connecting pieces. Such a connector is shown in Fig. 13 and designated 110. The connecting piece 110 is formed by two rings 112, 114 which are firmly connected to one another and which are aligned with their central axes perpendicular to one another and each run through with low friction on a string section 70 or 70 '.

In another embodiment of the tennis racket according to the invention, the strings are networked with one another in the usual way. In this case, the strings advantageously have a flattened cross-section, the dimensions of which are reduced in the direction perpendicular to the plane of the frame surface, so that the strings which are networked with one another are pressed against one another at the nodes only with a relatively small force.

The flattened strings advantageously comprise two cores of tensile strength which are square or round in cross-section and which are surrounded by a common casing made of friction-reducing material. The shell has a rectangular or elliptical cross section, or consists of two cross-sectional areas each receiving a core, which are interconnected by a web. bound s ind.

The use of two cores made of tensile material gives the string a twist resistance similar to that of a conventional string with a round cross-section.

In a modified embodiment, the string has only one core. A reduction in the junction friction can also be achieved with strings with a round cross-section if the diameter of the strings is reduced overall. In this case, the strings should consist of a particularly tensile material, possibly with a friction-reducing coating.

As has already been described with reference to FIG. 1, the strings in the racket according to the invention, for example the string 22, are extended beyond the frame surface into the handle 10. Between points C and D in FIG. 1, the string 22 is guided essentially without contact, so that the entire length A-B can participate in the elastic stretching of the string 22 when a ball hits it.

The extent to which the individual strings can be extended in this way is largely freely selectable, since the slide 18 is elongated and, as can be seen in FIG. 1, has a large number of fastening positions lying one above the other, for example bores 26. When the string is fastened in the lower region of the slider 18, the lengthening of the string increases accordingly.

After in this way for each string a suitable dehn¬ bare length and - when pulling the string - ^is' selected, a suitable Vorsp oltage, is after completion of stringing the possibility of stringing with a total HIL fes of the clamping bolt 20 in synchronism stronger or weaker to tighten. Again, the effect can be exploited that the tension in the string fixed in the upper region of the slider 18, the overall length of which is shorter, is increased or decreased more. Because of the friction at the crossing points of the strings - in particular if none of the above-mentioned measures to reduce friction are taken - the pretension emanating from the tensioning device in the handle 10 of the racket is increasingly reduced to the apex of the frame 12 opposite the handle 10 Such a voltage drop or voltage gradient can be used in a targeted manner if, for example, larger or smaller shock losses and / or smaller force increases are sought in the edge area of the sowing.

FIG. 3 is an enlarged illustration of the slider 18 already shown in FIG. 1. The slider 18 has a number of bores 26 lying one above the other in the longitudinal direction, which allow the strings to be guided through at different heights. In FIG. 4, which shows a further side view of the sliding piece 18, two adjacent bores are shown in the lower region, which allow two different strings to be accommodated at the same height. For the rest, a threaded bore 44 for receiving the clamping bolt 20 is indicated in the lower region of FIGS. 3 and 4. .

Fig. 5 shows another embodiment of a slider, which in this case is designated 18 '. Instead of the bores 26 according to FIGS. 3 and 4, undercut recesses 26 'are provided in this case on the two opposite strings, which allow the individual strings to be hung in at any height. A threaded bore 44 in turn serves to receive a clamping bolt, not shown.

OMP - // ~

As such, the slider can also consist of elastic material, such as rubber or elastic plastic, so that it has a certain spring and damping effect and can absorb impact losses. Since a deformation in the longitudinal direction of the slider from the bottom up in FIGS. 3 to 5 is added, this effect is particularly evident in the upper region of the sliders shown. This can be used specifically.

6 shows a schematic cross section through the frame 12. The frame consists of two box profiles 46, 48 connected by a web. The web for receiving a roller 50 is interrupted at the level of the cutting height in FIG. 6. In the example shown, the roller is spherical and has a circumferential groove 52 for guiding a string (not shown). The roller 50 is rotatably arranged on an axle pin 54 which is inserted into opposite bores of the box sections 46, 48, which are not described in more detail. A corresponding bore 56 is provided on the upper side of the box section 46 in FIG. 6 for inserting the axle pin. 7 is a side view of the frame 12 and shows the web 58 and circular recesses 51 for the rollers 50.

FIG. 8 shows a partial section through the web 58, not shown in FIG. 6, and in a view of one of the box profiles, which is designated by 60 in FIG. 8. An insert 64 made of slidable material is inserted into a bore 62 of the web 58 and has a bead-shaped rounding 68 in the region of the deflection of a string 66, which allows the string 66 to slide largely without friction. Such a solution results in a similarly low-friction connection between the string section 70 lying within the frame and the string section 72 lying outside the frame. 11 -

9 shows a similar deflection of a string 66. An insert denoted by 74 again engages in the bore 62, but instead of the rounding 68 has a support 76 which can be folded over in the direction of the arrow and is rounded at its free end and which, when pulled in In the direction of the interior of the frame surface, that is to say upward in FIG. 9 by flipping the movement of the string 66, there is practically no resistance, but in the rest position shown in FIG can be withdrawn while overcoming a certain amount of friction. It is thereby achieved that the string 66 yields slightly when a ball hits the string, but does not return with the same speed and lightness, so that the ball springs back only with a certain loss of impact.

A further embodiment of the deflection is illustrated in FIGS. 10 and 11. In these figures it is assumed as an example that the deflection is located in the vicinity of the lower apex of the frame 12, so that the string section extends freely from the frame to the slide piece 18. In this embodiment, the string 66 extends through a bore 100 of the support 76, which can be pivoted about an axis pin 102 in a region delimited by the web 58 and an inclined surface 104 of the support. By tilting the bore 100 with respect to the longitudinal direction of the string 66, the friction increases considerably when the support 76 is pivoted into the position shown in FIG. 10 by a pull on the string section 70.

If a further extension beyond the previously described lengthening of the string is required, a string 80 according to FIG. 12 can also be used several times in the hollow handle via rollers 82, 84 on the bottom plate - ß ^~

14 and in the area of the frame 12 back and forth v / er¬ the.

In the above description, the features of the invention were explained using a tennis racket. However, the invention can be applied in a corresponding manner to other rackets, in particular to Sguash rackets.

Claims

- / * PATENT CLAIMS

1. Tennis or squash racket with an essentially elliptical frame, a handle connected to it and a string made of crossing strings attached within the frame and having at least one low-friction deflected and multiple-tensioned string with essentially parallel strings String sections, characterized in that at least in part of the stringing (16) the immediately adjacent string sections (22c, 24d) belong to different strings (22, 24) and that the distance between the strings to the same ( 22) belonging parallel string sections (22a, 22b) is at least about a ball radius.

2. Racket according to claim 1, characterized in that the low-friction deflection of the strings takes place with the aid of rollers (28-40.50).

3. Racket according to claim 2, characterized in that the rollers (50) have a spherical shape.

4. Racket according to one of claims 1 to 3, characterized g e- indicates that the intersecting Sai¬ ten (70,70 ') run freely on each other in different planes and at the crossing points by connecting pieces (110) with each other are connected, which connecting pieces slidably receive the strings.

5. Racket according to one of claims 1 to 3, characterized in that the strings are flattened in cross section such that their dimensions in plane E of the frame surface are greater than perpendicular to this plane and that the strings at least a core made of tensile material and a sleeve le from friction-reducing material include.

6. Racket, in particular according to one of claims 1 to 5, characterized in that the strings (22, 24) are at least partially extended beyond the frame surface and that the string sections (72) extending beyond the frame surface are freely stretchable and with the string sections (22b, 22c, 70) lying in the frame surface are connected via a low-friction deflection (32, 34, 68, 76).

7. Racket according to claim 6, characterized in that the seat portions (72) extending beyond the frame surface are inserted into the hollow handle (10).

8. The racket according to claim 7, characterized in that the seat portions (72) extending beyond the frame surface are guided into the handle (10) along the outer surface of the frame (12).

9. Racket according to one of claims 6 to 8, characterized in that the deflection of the strings takes place via one-way friction brakes (76), which releases a shift of the strings in the direction of the interior of the frame surface, brakes in the opposite direction.

10. Racket according to one of claims 7 to 9, characterized in that the strings in the handle (10) are fastened to a longitudinally displaceable tensioning device (18, 20) in the handle.

11. Racket according to claim 10, characterized in that the tensioning device is an elongated, longitudinally displaceable slide in the handle - it. -

(18) which, in order to vary the length of the string sections (72) going beyond the frame (12) in different longitudinal positions, permits the strings to be attached or deflected.

12. Racket according to claim 11, characterized in that the slide (18) consists of elastic material and / or is elastically fastened.

13. Racket according to one of claims 1 to 12, characterized in that the strings are stretched diagonally to the longitudinal axis of the racket.