WO2000045658A1

WO2000045658A1 - Cloth for sportswear, use of said cloth in producing sportswear, and also said sportswear

Info

Publication number: WO2000045658A1
Application number: PCT/NL2000/000071
Authority: WO
Inventors: Johan Gierveld
Original assignee: Gierveld Beheer B.V.
Priority date: 1999-02-08
Filing date: 2000-02-04
Publication date: 2000-08-10
Also published as: NL1013310C1; AU2580300A

Abstract

The invention relates to a fabric of per se pliant material for aerodynamic equipment and devices, such as clothing for speed sports, including: skating, cycling and athletics, which fabric is at least partially provided with a pattern of recesses. This fabric thus displays a certain roughness, which in particular embodiments is even macroscopic, which results in a substantial effective decrease in the drag which can substantially increase the speed attainable with a given wind-force, muscular strength or muscular power, or can markedly reduce the energy required to attain suc h a speed.

Description

CLOTH FOR SPORTSWEAR, USE OF SAID CLOTH IN PRODUCING SPORTSWEAR, AND ALSO SAID SPORTSWEAR

It is known that in speed sports such as skating, cycling, athletics and the like the drag is an important factor at top levels of sport which co-determines the speed to be reached. In order to reduce the drag as much as possible, standard suits for said speed sports are always embodied such that the outer surface is substantially smooth. Fabrics which are preferably as smooth as possible are also used in other aerodynamic applications, such as a sailcloth for sailing vessels, a skin for airships such as zeppelins, a tensioned fabric for hang-gliders and gliders and parachute fabric etc.

The invention is now based on the insight that the drag can be decreased substantially, not by giving the fabric in question a smooth outer surface, but rather by giving it a certain effective roughness.

In this respect the invention provides a fabric as according to claim 1.

This fabric thus displays a certain roughness, which in particular embodiments is even macroscopic, which results in a substantial effective decrease in the drag which can substantially increase the speed attainable with a given wind- force, muscular strength or muscular power, or can markedly reduce the energy required to attain such a speed. In a preferred embodiment the fabric is per se elastic and tensioned during use. The pattern of recesses is herein profiled by the tensioning or only then becomes discernible, in any case in terms of the effect in respect of reducing the drag. A preferred embodiment relates to the dimensioning of the recesses. The values as according to claims 3 and 4 can be envisaged. The fabric can be a non-woven or also comprise a woven material. In this latter case the woven material can be of the jacquard type. If use is made in standard suits of smooth material with a density of about 190 g/m², the order of 220 g/m² can then be envisaged in the case of the jacquard woven material.

Claim 8 gives a practical option of creating the recesses .

Claims 10, 11, 12 and 13 give alternative practical options. It will be apparent that in the case an uninterrupted layer is arranged on a carrier, the layer in question must form a laminate together with the carrier and that there must therefore be adhesion over the whole surfaces of the layers concerned. The preferred embodiment is given in claim 14, Claims 15 and 16 give practical embodiment options.

Claim 17 claims the use of the flexible fabric for the manufacture of sportswear therefrom.

Claim 18 makes clear that it is deemed important according to the invention that the sportswear with an outer surface provided with a pattern of recesses lies tightly, essentially without folds and elevations and under elastic tension, against the body of a wearer. The structure according to claim 19 relates for instance to the forward-leaning position assumed by sportsmen such as skaters and cyclists during practising of their sport, i.e. the situation in which the torso is bent forward. It is advantageous if the elastic tension is substantially homogeneous and that in any case there is little difference in the tensile stress in the fabric on the chest side and on the back side.

So as not increase the drag unnecessarily, use can advantageously be made of the measures according to claims 20, 21, 22 and 23. The arranging of information, such as numbers, texts, advertising messages and the like, normally takes place by printing. It is conceivable for this to have a drag-increasing influence, and in any case a non- controllable effect. In this respect it is recommended that the information in question essentially forms part of the fabric and sportswear structure according to the invention. This important option is stated in claim 24.

The invention will be further elucidated hereinbelow with reference to the annexed drawing, in which inter alia various embodiments and applications of the fabric according to the present invention are shown, wherein: fig. 1 shows a schematic view of a suit as sportswear according to the present invention; fig. 2 shows a schematic view of a suit as sportswear in another embodiment according to the present invention; fig. 3 is a schematic perspective view of the pattern of recesses in the fabric in an embodiment of the invention; fig. 4 shows a perspective view of another field of application of fabric according to the present invention; fig. 5-7 show schematic views elucidating the practical use according to the present invention.

Fig. 1 shows a suit 1 manufactured from fabric 2 according to the present invention.

Fabric 2 displays a pattern of recesses with which in surprising manner the drag is decreased. Suit 1 is intended and suitable for use in the skeeler (in-line skating) sport. In such speed sports a reduction in the drag means that with the same effort of the sportsman a better, faster result can be achieved.

Suit 1 also comprises smooth portions 3 on the chest and thighs. These are thus the portions of the suit 1 which come into frontal contact with an oncoming air flow.

Alternatively, suit 1 can also be manufactured wholly from the fabric 2 with the pattern of recesses, although the portions of the suit making first frontal contact with the oncoming air flow are less effective than the other parts of the suit in reducing the drag. What is in fact achieved with fabric 2 is that an air flow which is flowing past the periphery of a torso, legs etc. of a sportsman adheres longer thereto, wherein a narrower wake is created behind the sportsman and the drag is thus reduced.

Fig. 2 shows a suit 4 which shows a particular resemblance to the suit shown in fig. 1. Suit 4 of fig. 2 is intended and suitable for the skating sport, for which purpose a hood 5 and leg pieces 6 down to the feet are provided.

The suit 4 of fig. 2 is also manufactured from the fabric 2 according to the present invention with a pattern of recesses. The optional flat portions 3 are also shown in fig. 2.

It is noted concerning the hood 5 of suit 4 that this also extends over the chin of the sportsman at reference numeral 7.

The fabric 2 used in suits 1, 4 of fig. 1, 2 displays a pattern of recesses such as is shown schematically by way of example in fig. 3. The recesses are designated with reference numeral 8. The fabric according to the invention shown in fig. 3 is only one embodiment. This is a jacquard woven material. It is noted that many other types of woven material and patterns of recesses can be applied within the scope of the present invention. It is thus possible to use fabric of the crepe-georgette type and/or the recesses 8 in fig. 3 can additionally or alternatively be designed in a honeycomb pattern. Nor is the invention limited to these latter options above.

With reference to fig. 1 and 2 it is noted that the fabric 2 of suits 1 and 4 is per se elastic and is tensioned round the body of the relevant sportsman. The recesses 8 of the fabric, as shown in fig. 3, are hereby well profiled and optimum use is made of the per se already good aerodynamic form of the human body of the sportsman without suit parts flapping in the air flow (energy loss, higher drag) . It is remarked that the fabric with recesses 8 shown in fig. 3 or any other design of a fabric according to the present invention has recesses 8 with a depth of approximately a maximum of 0.1-0.5 mm. Recesses 8 can have dimensions in width and length direction of about 6 mm. In an alternative embodiment, such as that wherein the recesses have a honeycomb pattern, this dimension can relate to a diameter.

Recesses 8 in fig. 3, or other recesses in an alternative or additional embodiment of fabric according to the invention, can be realized in different ways. The fabric can for instance comprise different threads such that during washing or finishing said recesses are created by selective shrinkage. Use can also be made of a non-woven fabric, wherein the recesses are made in the non-woven fabric, for instance with a roller. Use can also be made of a carrier, wherein a layer with holes therein is arranged thereon. The carrier lies exposed at the holes in the cover layer, whereby said recesses are formed. It is then precisely not such an interrupted layer which forms the recesses as indicated in fig. 3 with numeral 8, but the elevations 9 adjacent thereto. The carrier is exposed at the holes in the cover layer to thus form recesses 8. The interrupted layer which can serve as cover layer can be a cured mass which remains elastic, for instance a synthetic rubber, which is applied to the carrier in a pattern corresponding with the recesses. Diverse materials can also be used for the fabric according to the present invention. When it is desirable, as in the applications of fig. 1 and 2, for the fabric to be elastic, the fabric can comprise elastomer threads, for instance with lycra. Such an elastomer can be present in the fabric in a content of between approximately 10 and 20%. In such an embodiment with 10-20% elastomer the remaining threads can consist of polyamide. Many other materials, textiles and woven materials can also be applied as fabric according to the present invention, depending on the field of application. It is thus desirable in speed sports that the suit formed from the fabric be elastic. Fig. 4 however shows an application, i.e. an airship 10, with an aerodynamic form. The skin 11 of airship 10 is manufactured from fabric according to the present invention. This demonstrates that there are many other fields of application, in addition to the fabric for manufacturing sportswear particularly for speed sports, where the fabric according to the present invention can be applied. The fabric can thus also be used as covering for hang-gliders, gliders, as fabric for parachutes and even as sail for sailing vessels. In short, the fabric according to the present invention can be used in practically all applications where the covering or outer surface of an object and an air flow move relative to each other and wherein the drag is important in respect of the performance relating to speed and the energy- consumption required therefor.

There now follows an explanation of the principle of use of the fabric according to the present invention. Fig. 5 shows a cylinder 12 of circular cross- section as approximation of or model for a sportsman or an object placed in an air flow 13. In the configuration shown in fig. 5 the Reynolds number, which is defined as U x D : v, wherein U is the wind speed, D the characteristic length and v the kinematic viscosity, lies in the subcritical region. In this subcritical region, as shown in the graph of fig. 7, a laminar boundary layer of air 14 flows along cylinder 12. At the said Reynolds number in the subcritical region the boundary layer of air begins to separate from cylinder 12 at arrow A, which results in a wide wake 15, as shown in fig. 5. Such a wide wake 15 is associated with a high drag, as will be apparent from the graph of fig. 7. In graph 7 the drag coefficient is plotted along the vertical axis and designated c_w. The Reynolds number is plotted along the horizontal axis in a logarithmic scale and designated Re.

At higher values of the Reynolds number in the critical region, i.e. between 2 x IO⁵ and IO⁶, a considerable decrease in the drag coefficient c_w is noticeable. The situation prevailing here is shown in fig. 6 in a manner comparable to that of fig. 5. The laminar boundary layer of air 14 becomes turbulent and adheres against cylinder 12 during a movement around it. A so-called "release bubble" is herein formed, as shown in fig. 6. The wake 15 is markedly narrower in fig. 6 than in fig. 5, which results in a considerably lower drag coefficient.

The minimum of the drag coefficient c_w lies at that Reynolds number wherein the "release bubble" has just disappeared. With a further increase in the Reynolds number through the supercritical and transcritical region in fig. 7, the influence of the Reynolds numbers on the drag coefficient c_w decreases progressively. These regions are of less importance for the present invention.

The present invention is based on the insight that the curve of the graph of fig. 7 can be influenced as according to the dashed lines with the roughness of the surface of the cylinder 12 of circular cross-section. As the roughness of the outer surface or mantle surface of cylinder 12 increases, which is indicated schematically with arrow B, the graph moves along the curves shown in dashed lines in the graph. The pattern with recesses in the fabric according to the present invention enhances the change to a turbulent boundary layer as shown in fig. 6, wherein the total resistance decreases as shown in fig. 7. This is all the more astonishing and/or surprising in view of the increase in the actual frictional resistance on the surface or mantle surface of cylinder 12. Fig. 7 shows clearly that with the moving of the graph along the options shown in dashed lines and each associated with a determined surface roughness of cylinder 12, the transition between the subcritical and the critical region also moves, wherein a lower drag coefficient c_w can thus be achieved at lower values of the Reynolds numbers. For many sports and other aerodynamic applications it is the case that with the smoothest possible covering or sportswear the Reynolds number is located in the subcritical region, while with a fabric according to the invention as covering the boundary between the subcritical and critical region is decreased in respect of the Reynolds values, so that at the same Reynolds value a lower drag coefficient c_w is realized by applying the pattern of recesses in the fabric according to the present invention. The invention is described in the foregoing with reference to a number of embodiments. The invention is however not limited thereto, but is defined by the appended claims. Many patterns can thus be applied other than those shown in fig. 3, for instance honeycomb-like and so on. In addition to sportswear and zeppelins the fabric according to the invention can also be used as sail for a sailing vessel, as covering for hang-gliders and gliders and even as fabric for parachutes. The dimensions of the recesses in the pattern according to the invention can also vary from those described in the foregoing, as can the height/depth of the recesses. It lies within the capability of the ordinary skilled person to realize per field of application a pattern of recesses which achieves a reduction in the drag coefficient within the range of Reynolds numbers occurring in such an application. Secret tests with skating outfits have shown that in speed-skating lap times on a circuit of 400 metres, which may be in the order of for instance 35 s, can be improved by 0.5-0.7 s. This must be considered at this time a very spectacular improvement, which is achieved by the above described insight according to the invention that the recesses on the outer surface of the tight-fitting sportswear have the effect that the boundary layer between the clothing and the air flowing past is effectively made thicker. With smooth clothing the air in question effectively flows past the clothing with a very thin boundary layer, while with the structure according to the invention the air present in the recesses as it were forms a stationary air cushion, whereby the passing air can flow past more easily and with less resistance and the desired occurrence of turbulence .

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Claims

1. Fabric of per se flexible material for aerodynamic equipment and devices, such as clothing for speed sports, including: skating, cycling and athletics, ^•which fabric is at least partially provided with a pattern of recesses.

2. Fabric as claimed in claim 1, wherein the fabric is per se elastic and tensioned during use.

3. Fabric as claimed in claim 1, wherein the recesses have maximum depths of about 0.1-0.5 mm.

4. Fabric as claimed in claim 1, wherein the recesses have maximum widths and lengths or diameters of about 6 mm.

5. Fabric as claimed in claim 1, wherein the fabric comprises a woven material.

6. Fabric as claimed in claim 1, wherein the fabric comprises a Jacquard woven material.

7. Fabric as claimed in claim 5, wherein the fabric is of a crepe-georgette type.

8. Fabric as claimed in claim 5, wherein the woven material consists of different threads such that during washing or finishing said recesses are created by selective shrinkage.

9. Fabric as claimed in claim 1, wherein the fabric comprises a non-woven.

10. Fabric as claimed in claim 1, wherein the recesses are arranged by heat and pressure by a profiled pressure surface, for instance the mantle of at least one roller.

11. Fabric as claimed in claim 1, wherein a layer interrupted by holes is arranged on a carrier, which holes correspond with said recesses.

12. Fabric as claimed in claim 11, wherein the interrupted layer comprises a mesh structure or a perforated fabric.

13. Fabric as claimed in claim 11, wherein the interrupted layer is a cured mass which remains elastic, for instance comprising a (synthetic) rubber.

14. Fabric as claimed in claim 1, wherein the fabric comprises elastomer threads, consisting for instance of lycra.

15. Fabric as claimed in claim 14, wherein the proportion of elastomer amounts to about 10-20%.

16. Fabric as claimed in claim 14, wherein the remaining threads consist of polyamide.

17. Use of the fabric as claimed in any of the claims 1-16 to manufacture sportswear, the outer surface of which is provided with a pattern of recesses.

18. Sportswear manufactured from fabric as claimed in any of the claims 1-16 and embodied such that it lies tightly and under elastic tension against the body of a wearer.

19. Sportswear as claimed in claim 18, wherein the front side of the torso part is a certain amount, for instance 40 mm, shorter than the back side such that in a forward-leaning position, as in skating and cycling, the torso part closes round the torso of the wearer with a substantially homogeneous elastic tension.

20. Sportswear as claimed in claim 18, comprising a zip fastener extending over at least a part of the height of the torso part, which zip fastener is situated on the back side.

21. Sportswear as claimed in claim 18, comprising a hood fitting tightly round the head under elastic tension which has a form such that it also covers the chin of a wearer.

22. Sportswear as claimed in claims 20 and 21, wherein the zip also extends over the rear side of the hood.

23. Sportswear as claimed in claim 18, wherein the constituent parts connect mutually with seams with negligible elevations, particularly at the front.

24. Sportswear as claimed in claim 18, wherein information, such as a number, texts and/or advertising, is arranged in the fabric by embroidering, or co-weaving during manufacture of the woven material.

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