CA2108879A1

CA2108879A1 - Racket

Info

Publication number: CA2108879A1
Application number: CA002108879A
Authority: CA
Inventors: Karl-Heinz Wager
Original assignee: Karl-Heinz Wager; Head Sport Aktiengesellschaft
Current assignee: Head Sport GmbH
Priority date: 1992-02-21
Filing date: 1993-02-22
Publication date: 1993-08-22
Also published as: WO1993016765A1; AT404230B; ATA33792A; SK115893A3; EP0581927A1

Abstract

ABSTRACT

In a racquet, in particular a squash racquet, the total weight of the racquet when unstrung is less than 165 g, and the head weight is less than 83 g, in particular less than 78 g, whereby for a low weight it is also possible to obtain improved ball acceleration with a high level of orientation precision and pleasant playing characteristics.

Description

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A RACQUET

The present invention relates to a racquet, in particular a squash racquet. As a rule, racquets of this ~ind have a relatively large handle section and a strung frame that is relatively small in proportion to the length of the racquet.

In known racquets of the type described in the introduction hereto, in principle, the properties that are relevant for a ball ~ -game, in particular, the elasticity of the handle section, ball acceleration, and oscillation and damping behaviour, have been controlled mainly by the material and cross-sections used in the handle section, between the strung frame and the handle end itself. Various materials have already been used in the construction o~ racquets of this kind. In particular, it has been the practice to build racquets of relatively low weight, when a light racquet of this kind results in good racquet acceleration but also in ball acceleration that is not entirely satisfactory, to say the least. When this was done, light racquet weight was achieved only in racquets with a small impact surface.

When racquets were constructed in the past, there were frequent attempts, particularly when producing tennis racquets, to increase the inherent or characteristic frequency by using new and lighter materials. In tennis racquets, an increase of the inherent frequency of this kind was aimed mainly at ensuring a higher level of arm protection in racquets. In the case of squash racquets, because of the different dimensions and the essentially lower weight of the racquets, the conditions that apply to this kind of racquet are completely dlfferent, and a simplQ alteration of the weight,lbrought about by the selection o~ lighter and, iP nacessary, sti~er materials does not always

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of necessity lead to an improvement in playing characteristics.
Because of the relatively small impact surface, an important prerequisite when designing squash racquets is that a high level of orientation stability be ensured at higher ball acceleration, even i~ the ball strikes the strung frame at different points.
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It is the task of the present invention to develop a squash -racquet of the type described in the introduction hereto such that it ensures improved ball acceleration at the highest level of precision with respect to orientation and, at the same time, imparts good playing characteristics. According to the present invention, in order to solve this task, it i5 proposed that the total weight of the racquet, when unstrung, be less than 165 g;
and that the racquet have a head weight of less than 83 g, and in particular less than 78g. In this definition, head weight is understood to be that weight which can be measured at the head end as reaction force [bearing load] when the racquet is supported at the handle end, with the racquet in a horizontal position. A racquet whose head weight, measured in this way, is greater than half tbe racquet weight must be considered as slightly head-heavy: in contrast to this, racquet with a head weight that is less than half the racquet weight, as measured by this method, would have to be considered as handle-heavy. The solution according to the present inventlon, when the racquet, in the unstrung state, is designed to have a weight o~ less than 165 g, in particular less than 165 g, with a head weight that is less than 83 g, means, in other words, that what is involved here is a racquet that is almost balanced when strung. What is obtained by doing this is a racquet with which rapid reaction play is made possible since, because of the low racquet weight and the weight distribution within the racquet, as proposed by the present invention, the racquet can be moved towards the ball at much greater speed. Racquets known up to now have used significantly greater head weights in order to arrive at acceptable playing characteristics. Even in the case o~ the extremely light ... , '.

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racquets that have been known up to now, the head weights were always much greater than the ma~imum head weight that is proposed by the present invention and, in addition to significantly heavier racquets, there are already racquets on the market which, although distinguished by a total weight of less than 165 g, and in particular less than 165 g, nevertheless also have a head weight of much more than 83 g. The balance of the racquet that is achieved by the combination proposed by the present invention leads to a greater level of stability, despite the low racquet weight, and to precise playing characteristics of the sort that up to now could only be achieved with significantly heavier racquets. At the same time, despite the low weight of the racquet, much the same good ball acceleration has also been observed; in this connection, it is advantageous that the significantly lighter racquet as proposed by the present invention be strung at much higher stringing forces. Whereas conventional squash racquets are normally strung at approximately 12 kg, the racquet according to the present invention should, advantageously, be strung at approximately 14 kg.

According to a preferred embodiment, the configuration i5 such that the racquet has an impact surface of no less than 330 cm2, and in particular at least 350 cm2. Using a large-area racquet of this kind, which is of low weight, the advantages with respect to ball safety and acceleration are greater.

An additional and obvious improvement of playing characteristics and, in particular, an especially high level of ball acceleration can be achieved according to the present invention in that the .
moments of inertia at the handle end, in a plane that contains .
the stringing and in a direction that is normal to this are :.
smaller than 30 gm2, and in particular smaller than 28.5 gm2.
The values proposed by the present invention thus lie clearly . .
below formerly known values, although initially it was ~eared that smaller inertial moments of this kind could result in lower

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ball acceleration and lower impact precision or stability. Most surprisingly, however, the opposlte was achieved, whereby a significantly lighter squash racquet that can be rapidly accelerated can be achieved while complying with the cumulative conditions, together with the cond~tions for the upper limit of the total weight and the head weig~t. When this is done, determination of the inertial moments is effected while securing the racquet at the handle end by measuring the pendulum move~ent of the racquet during a movement in the plane that contains the stringing and in a direction that is normal to the stringing plane.

According to the present invention, within the context of the conditions for designing the squash racquet, it is also advantageous to comply with the conditions that for a racquet, in an unstrung state, with a centre of gravity distance of less than 390 mm, as measured from the handle end, the ratio of the unstrung racquet weight to the head weight is less than 2.07, and the ratio of the centre o~ gravity distance to the unstrung racquet weight is greater than 2.1, when it is preferable that the centre of gravity distance of the unstrung racquet ~easured from the handle end is between 340 and 380 mm. Finally, it is an advantage that the ratio of head weight to inertial moment be less than 2.81 in the plane of the stringing~ All of these criteria have been shown to be particularly advantageous for :
achieving neutral playing characteristics and, taken together, they result in a balanced, fast-accelerating squash racquet that provides a high level of impact precision.

Compared to known racquet designs with relatively large strung areas, the above-defined ratio of head weight to inertial moment, measured, in each instance, on an unstrung racquet, results in a more characteristic but relatively smaller difference to corresponding values measured on known racquets which, however, without exception differ from the object of the present invention 21~8~, ~

with respect to their weights. Whereas correspondingly large-area racquets can easily , without exception, be made with significantly higher racquet weights and higher head weights, it has, most surprisingly, been shown that the greatly improved playing characteristics with respect to impact precision and quick racquet acceleration as well as rapid ball acceleration, which can be achieved by the present invention, can be achieved only by keeping within clearly defined limits, such as, for example, the upper limit for the head weight to the inertial moment.

Since, all in all, as has been set out in detail above, it is primarily the weight, the head weight, and the impact surface that help improve racquet characteristics, other criteria that make it possible to identify superiority with reference to the quoted playing characteristics were also considered in detail.
In this way, it was determined that particularly favourable properties can be achieved if the ratio of the strung area to the inertial moment, measured normally to the plane of the stringing, is greater than 14, and in particular greater than 15. The proportional values that are cited are, without exception cited as absolute numerical values, which when considering the physical values used in each instance for forming the ratios, would strictly speaking come to a corresponding dimension. All known designs with a racquet weight of less than 200 g have, most surprisingly, resulted in a proportional value of at most 13.5 as the upper limit, which in the fact means that the proportional figure of greater than 14, determined according to the present invention, has to be evaluated as being significant for the improvement that can be achieved with relation to playing characteristics. This applies, in particular, in the case of the preferred minimum value for the ratio of strung area to inertial moment of 15. Similarly, during investigation of the racquet according to the present invention, it was determined that the ratio of strung area to head weight is advantageously greater ~l~g~7~ ~

than 4.5, and preferably greater than 5.2. Here too, it has been found that particularly with reference to the preferred value of at least 5.2, a high value of this kind is not achieved by any of ~.
the known large-area squash racquets, so that in combination with the conditions referred to above with respect to racquet weight, head weight, and/or the impact surface, this value has to be assessed as characteristic. .

Claims

PATENT CLAIMS

1. A racquet, in particular a squash racquet, characterized in that the total weight of the racquet when unstrung is less than 170 g.

2. A racquet as defined in claim 1, characterized in that the racquet has an impact surface of no less than 330 cm2, in particular at least 350 cm2.

3. A racquet as defined in claim 1 or claim 2, characterized in that the inertial moments about the handle end in a plane that contains the stringing and in a direction that is normal to this is, in each instance, smaller than 30 gm2, in particular smaller than 28.5 gm2.

4. A racquet as defined in claim 1, claim 2, or claim 3, characterized in that for racquets with a centre of gravity distance, measured in the unstrung state from the handle end, of smaller than 390 mm, the ratio of the unstrung racquet weight to the head weight is smaller than 2.07, and the ratio of the centre of gravity distance to the unstrung racquet weight is greater than 2.1.

5. A racquet as defined in one of the claims 1 to 4, characterized in that the centre of gravity distance of the unstrung racquet as measured from the handle end is between 340 and 380 mm.

6. A racquet as defined in one of the claims 1 to 5, characterized in that the ratio of head weight to inertial moment is smaller than 2.81.

7. A racquet as defined in one of the claims 1 to 6, characterized in that the ratio of the strung area to the inertial moment, as measured normal to the plane of the stringing, is greater than 14, and in particular greater than 15.

8. A racquet as defined in one of the claims 1 to 7, characterized in that the ratio of the strung area to the head weight is greater than 4.5, in particular greater than 5.2.

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