EP0661086A1 - Ski - Google Patents

Abstract

Ski comprising: . a first lower assembly (10) including a planar running sole (11) having a plane of symmetry P perpendicular to the plane of the running sole and passing through its median longitudinal axis, . a second upper assembly (15) forming a top (16) and sidewalls (17), . these two assemblies defining an intermediate space (20) in which the neutral fibre (FN) is located, characterised in that the inclined longitudinal reinforcement element consists of a flat strip (25) which, while defining an acute angle with respect to the plane of the running sole (11), is arranged asymmetrically with respect to the plane (P) of symmetry of the lower assembly (10). <IMAGE>

Description

Technical area

The invention relates to an improved ski, in particular a ski with an asymmetrical structure.

Previous techniques

• . un premier ensemble inférieur, constitué par une semelle plane destinée à assurer la glisse éventuellement bordée de carres métalliques, et par au moins un élément de renfort longitudinal inférieur, l'ensemble présentant un plan de symétrie perpendiculaire au plan de la semelle et passant par l'axe longitudinal médian de cet ensemble inférieur ;
• . un second ensemble supérieur constituant le dessus et les chants ;
• . enfin, un espace intermédiaire de remplissage compris entre le premier et le second ensembles, dans lequel est située la fibre neutre (FN) et qui comporte un autre élément de renfort.

As we know, in cross section, a ski can be in three essential parts, namely respectively:

• . a first lower assembly, consisting of a flat sole intended to ensure sliding, possibly bordered by metal edges, and by at least one lower longitudinal reinforcing element, the assembly having a plane of symmetry perpendicular to the plane of the sole and passing through the 'median longitudinal axis of this lower assembly;
• . a second upper assembly constituting the top and the edges;
• . finally, an intermediate filling space between the first and second sets, in which the neutral fiber (FN) is located and which includes another reinforcing element.

For a few years now, we have known skis in which the second upper assembly follows the shape of a shell which bears on the two lateral edges of the first lower assembly.

As we know, a ski is subject to several types of deformation. It is, during an effort, mainly subjected to a simple normal flexion, which is exerted perpendicular to the sole on a ski placed between two supports, flat on its sole; this deformation allows it to follow the relief of the terrain; the resistance of a ski to this deformation, that is to say its stiffness in bending or its distribution of flexibility, is calculated to distribute the load of the skier on the snow.

A ski is also subjected to a simple lateral bending, which is exerted laterally on the side of the ski and causes bending of the median longitudinal axis of the lower assembly; this deformation, which is not controlled, is harmful and impairs the accuracy of the ski. Furthermore, a ski receives twists or twists, in particular at its two tips tip and heel. As before, these deformations are parasitic and affect good use of the ski. Finally, a ski is subjected to compound deformations: bending plus torsion, or normal bending plus lateral bending, etc ....

In addition, for the most part, modern skis have a wide area at the tip and heel and a narrow area at the skate. More generally, the width of the tip is greater than that of the heel, which, in turn, is greater than that of the skate. The edge line joining the tip to the heel, called "dimension line", is an essential characteristic of a ski. It varies from one manufacturer to another, in particular depending on the specific use envisaged. Thus, a slalom ski does not have the same dimension line as a downhill ski, just as that of a recreational ski is different from that of a competition ski.

This dimension line is of considerable importance in the practice of skiing. It is therefore important that during practice, it is not changed randomly during deformation of the ski.

As we know, in a beam, the "neutral fiber" (FN) is the area where the compressive and tensile stresses cancel each other out. This fictitious area is determined according to the shapes and the internal composition of the beam. As a ski behaves like a beam, it follows that it has a "neutral fiber", designated below (FN).

In a ski, the mechanical reinforcements are generally located in the intermediate space, and this on either side of the neutral fiber, in particular to ensure good mechanization. To optimize the effectiveness of the reinforcements, it is important to position them as far as possible from the neutral fiber (FN), because in a calculation of bending stiffness, the distance from the reinforcement to the neutral fiber is squared.

Most generally, a ski is symmetrical relative to the plane of symmetry perpendicular to the plane of the sole and passing through the median longitudinal axis thereof.

In recent years, to meet technical and aesthetic requirements, asymmetrical skis have been proposed, that is to say skis whose shape and volume vary in thickness, length and width on one side to the other of the same ski, but whose rib line nevertheless remains symmetrical. In such skis, the manufacturers, in order to keep a simple normal bending, that is to say without lateral bending or without parasitic torsion, were forced to design an opposite internal armed structure, correcting the dynamic effects of the asymmetry of shape .

Indeed, to avoid parasitic lateral bending occurring during normal bending, it is necessary that the mechanization elements, that is to say the reinforcements, are placed so that the bending stiffnesses are symmetrical with respect to in the median vertical plane passing through the median longitudinal axis of the sole.

Furthermore, in document FR-A-2 611 517, corresponding to document US-A-5,108,124, a ski has been described having against the hull and on each of the two edges a variable inclined reinforcement, symmetrical with respect to the median plane P of the sole. This ski behaves in use, like a traditional symmetrical ski.

In document FR-A-2 687 924, the Applicant suggested inserting into the intermediate space filled with foam at least one possibly asymmetrical tubular reinforcement, perforated, disposed respectively in front and behind the skid area. This embodiment aims to improve the guidance of the ski without stiffening it, to make it more comfortable. However, it does not ensure optimal transmission of support on the edges, because as we know, it is at the level of the skate that these supports are most powerful.

In document FR-A-2 589 745, in order to improve the resistance, it has been proposed to use intermediate pieces to ensure a good distribution of the stresses, which can form edges of lower or higher angle. This theoretical arrangement is difficult to achieve, due to the non-negligible risks of take-off of these intermediate pieces as a result of the shears induced by the permanent bending stresses.

In document FR-A-2,590,179, to ensure good transmission of forces to the inner edge of a cross-country ski, it has been proposed to drown in the intermediate space and at the level of the shoe a ribbed reinforcement in the shape of a U inverted of particular architecture and whose edge of the large branch is supported on the internal edge. This favorable arrangement for the practice of the skater's step is not concerned with orienting or controlling the deformations during the supports, because its short length does not exceed the skate area, which cannot modify the behavior of the ski.

It can therefore be said that, in the prior art known to date, all skis have been designed to avoid generating parasitic lateral bending during a normal bending deformation. Thus, we can say that the dimension line, that is to say the respective position of a point of the lower edge relative to another point located in front or behind it, retains its characteristics without modification.

Statement of the Invention

The invention takes the opposite view to this rule in order to highlight the interesting effect of a controlled variation of the dimension line. It targets a ski, asymmetrical or not, which has the possibility of allowing the variation of the dimension line as a function of the impulse given by the skier or as a function of the conditions of use.

• . un premier ensemble inférieur, comportant une semelle plane présentant un plan de symétrie P perpendiculaire au plan de la semelle passant par son axe longitudinal médian,
• . un second ensemble supérieur formant un dessus et des chants,
• . ces deux ensembles définissant un espace intermédiaire, dans lequel est située la fibre neutre (FN) et dans lequel au moins au niveau du patin central, est disposé un élément longitudinal de renfort principal incliné par rapport au plan de la semelle,

se caractérise en ce que l'élément de renfort principal incliné est constitué d'une bande plate qui, tout en définissant un angle aigu par rapport au plan de la semelle, est disposée asymétriquement par rapport au plan médian (P) de symétrie de l'ensemble inférieur.This ski, which includes:

• . a first lower assembly, comprising a flat sole having a plane of symmetry P perpendicular to the plane of the sole passing through its median longitudinal axis,
• . a second upper assembly forming a top and edges,
• . these two assemblies defining an intermediate space, in which the neutral fiber (FN) is located and in which at least at the level of the central shoe, a longitudinal main reinforcement element is inclined relative to the plane of the sole,

is characterized in that the inclined main reinforcing element consists of a flat strip which, while defining an acute angle with respect to the plane of the sole, is arranged asymmetrically with respect to the median plane (P) of symmetry of the 'lower assembly.

In other words, the invention aims to provide a flat strip embedded in the filling component of the intermediate space, generating during simple bending stresses, an asymmetrical deformation relative to the plane of symmetry passing through the longitudinal axis. median of the lower assembly (sole). This strip extending from the first lower set towards the second upper set while defining an acute angle relative to the plane of the sole. This flat strip characteristic of the invention being inclined relative to the plane of the sole, induces a lateral component during stresses normal to the plane of the sole.

In the description and in the claims, by “flat strip”, is meant a thin solid strip, of flattened rectangular section, so that the deformation is exerted essentially on the two main parallel faces of this strip. In this way, when this inclined strip embedded in the foam filling the intermediate space, is subjected to a force (or a support) perpendicular to the plane of the lower assembly, it generates, in addition to the usual bending of the ski, a lateral displacement by decomposition of efforts or forces.

The invention differs from the solutions mentioned in the preamble comprising reinforcements with symmetrical inclinations which, when they are stressed in deformation under a force normal to the sole, do not generate a lateral component, because they neutralize each other. It is distinguished from those comprising reinforcements with asymmetrical, different and / or opposite inclinations, by the fact that the latter contradict each other and therefore do not have any significant lateral component.

In a practical embodiment, the characteristic flat strip extends from the spatula to the heel, and the inclination of this strip varies regularly from the spatula to the heel relative to the plane of the sole, respectively from zero degree to the level of the spatula and the heel, at 45 ° at the level of the skate.

• le ski comporte une seule bande plate coupant le plan P au niveau de son axe longitudinal médian en définissant deux portions de même largeur disposées de part et d'autre de ce plan P ;
• la bande plate de renfort présente une inclinaison constante par rapport au plan de la semelle, voisine de 45° sur partie ou toute la longueur du ski ;
• la bande plate est en métal, par exemple du type lame de scie, ou en un matériau plat statifié lamellaire composite ; ce peut être aussi un morceau de bois dont l'empilement des fibres se comporte comme un ensemble lamellaire.

Advantageously, in practice:

• the ski comprises a single flat strip intersecting the plane P at its median longitudinal axis by defining two portions of the same width arranged on either side of this plane P;
• the flat reinforcing strip has a constant inclination relative to the plane of the sole, close to 45 ° over part or the entire length of the ski;
• the flat strip is made of metal, for example of the saw blade type, or of a flat, laminated composite composite material; it can also be a piece of wood whose stack of fibers behaves like a lamellar assembly.

If more generally the strip is single, it can also be formed of individual strips which are necessarily parallel, therefore of the same inclination (see FIGS. 5 and 10) in order to behave like a single strip.

If most advantageously, the ski according to the invention is symmetrical, it can also be asymmetrical. Likewise, this ski can be of traditional form or of more complex form.

In one embodiment, the inclination of the characteristic flat reinforcement strip is constant relative to the plane of the sole, but the width of this reinforcement varies along the ski, at the same time as the height of this ski.

In another embodiment, the ski has several flat inclined reinforcing bands, of the same angle and of the same orientation relative to the plane of the sole, so that the deformations add up. Indeed, if the reinforcements were symmetrical with respect to the plane P, there would be cancellation of the lateral effects.

When the characteristic strip is placed in the neutral fiber, no effect is obtained in normal bending, but an increase in the resistance in lateral bending. On the other hand, when the characteristic flat reinforcing strip is placed in the intermediate space near the sole or at the level of the upper, the values are changed both in normal bending, and also in lateral bending.

The characteristic inclined flat strip can be embedded in the intermediate space forming the core either by injection in situ or by assembly (wooden or rigid polyurethane core, or in honeycomb structure). In this embodiment, a core is made beforehand comprising the characteristic inclined flat strip, and the assembly is inserted in the intermediate space in a conventional manner.

The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the embodiment which follows, with the support of the appended figures.

Brief description of the figures

• . au niveau de la spatule, en figure 2,
• . au niveau du patin, en figure 3,
• . au niveau du talon, en figure 4.

FIG. 1 is a schematic representation seen from above of a ski according to the invention, shown in section:

• . at the spatula, in Figure 2,
• . at the level of the skate, in FIG. 3,
• . at the heel, in Figure 4.

Figures 5 and 6 illustrate other embodiments of the invention.

Figures 7 and 8 show schematically the operation of the invention.

Figure 9 shows the layout of a pair of skis.

Figures 10,11,12 are three other forms of skis according to the invention.

Manner (s) of carrying out the Invention

The ski shown in FIG. 1 essentially comprises, in the longitudinal direction, a spatula (1), a central skid zone (2), and a heel (3).

In section, according to FIGS. 2 to 4, this ski firstly comprises a first lower assembly, designated by the general reference (10), constituted by a flat sole (11), bordered on each of its two lateral sides by metal edges, respectively (12) and (13). This lower assembly (10) has a plane of symmetry (P) perpendicular to the plane of the sole (11), passing through the median longitudinal axis (I-I ') of the ski and of the lower assembly (10).

In a known manner, the ski also comprises an upper assembly, designated by the general reference (15), formed of an actual top (16) and two lateral edges (17,18) bearing on the edges (12,13 ). These two sets, respectively lower (10) and upper (15), define an intermediate space (20), delimited by the top of the sole (11), by the internal face of the edges (17,18) and by the internal face. from above (16).

This intermediate space (20) comprises the neutral fiber shown diagrammatically by the axis (FN), parallel to the plane of the sole (11). As is known, this neutral fiber (FN) is at the ends (1) and (3) parallel to the plane of the sole (11) and is located substantially equidistant from this plane of the sole (11), and from the plane from above (16).

According to a characteristic of the invention, the intermediate space (20) comprises a solid solid flat strip of reinforcement (25) inclined, going from the tip (1) to the heel (3). This flat strip (25) is made for example of metal or of fibrous composite material of common application in the ski area. This characteristic reinforcement strip (25) extends from practically the tip (1) to the heel (2) with an inclination which varies regularly with respect to the plane of the sole (11), namely from zero degree to the level of the spatula (1) and the heel (3), at 45 ° at the level of the pad (2). This variation in the inclination of the flat strip (25) is progressive and continuous.

In a practical embodiment, this characteristic flat strip (25) is made of aluminum alloy commonly used in skiing called ZICRAL (registered trademark PECHINEY-CEGEDUR) 120 centimeters long, 30 millimeters wide and 0.8 millimeter thick. To allow the passage of the components of the injected foam, this strip (25) is perforated with a multitude of holes of 4 millimeters in diameter.

At the level of the shoe (2), this characteristic strip (25) (see FIG. 3) extends practically from the lower edge of the ski, namely the edge (12), near the lower assembly (10), up to 'at the opposite edge of the ski, near the upper assembly (15).

In known manner, the intermediate space (20) is filled with a filling material, such as for example a polyurethane foam.

Depending on the configuration of the ski, the width of the characteristic reinforcing flat strip (25) can also vary from the tip (1) to the shoe (2), then from this area to the heel (3). As already said, it is important that this inclined strip (25) is massive and possibly perforated.

In another embodiment shown in Figure 5, the intermediate space (20) filled with foam comprises two inclined reinforcements (30) and (31) similar to (25), which also vary from zero to 45 degrees, from the spatula or the heel to the skate. Here, these two inclined reinforcements (30,31) are parallel, extend from the sole (11) to the top (16) by defining an angle of at most 45 ° relative to the plane of the sole, and are arranged asymmetrically with respect to the plane P by cutting the neutral fiber (FN).

In a third embodiment shown in FIG. 6, the intermediate space (20) comprises a neutral core (35) commonly used for this application, for example made of wood, into which an inclined reinforcement (40) is inserted. similar to (25,30 or 31). The rest of the intermediate space (20) is in known manner filled with polyurethane foam. Alternatively, this core (35) reinforced by the inclined strip (40) can occupy the entire intermediate space (20).

Theoretical analysis of the operation of the ski according to the invention:

In the embodiment illustrated in Figure 1, the maximum width of the ski L1 at the tip is eighty-six millimeters, the maximum width L3 at the heel of eighty millimeters and the minimum width L2 at the sixty-two millimeter shoe (2).

This ski is placed between two supports, each located near a tip tip (1) and heel (2). FIG. 7 is a schematic representation of this ski (200) at the level of the skate, first shown in dashed lines, at rest (201), and then, under the action of a load F normal to the surface of the sole, corresponding to the weight of a skier. The characteristic strip of the invention (25) being inclined by 45 °, this load F is transformed into two components, respectively a normal component F1 and a lateral component F2. Under the action of these two components F1 and F2, the ski deforms so that the lower edge (131) of the ski (201) at rest will become the edge (130) of the ski (200) under load. This edge (130,131) will move in normal bending of an arrow f1 and in lateral bending of a displacement f2.

On the other hand, if the ski did not have the characteristic inclined reinforcing strip (25) under the effect of the same load F normal to the surface of the sole, it would retain a normal deflection g1 greater than f1, but would not have lateral displacement.

FIG. 8 shows, in top view, the ski according to the invention, in two positions, respectively at rest in mixed lines with its edge lines (121) and (131), and under load in solid lines, with its two lines of edges (120) and (130). The lateral displacement f2 is, in this case, assimilated to a modification of the dimension line of the ski which from (121) to (120), will widen even more, while on the opposite side (131) and (130), this dimension line tends to become more rectilinear, that is to say flatter. In this way, when skiing, to make a turn with a small radius, the skier will exert on the internal edge a significant pulse F which is broken down into F1 and F2. This causes a change in the dimension line at the level of the skate. If the skis are arranged according to the configuration of FIG. 9, the ski outside the turn, which receives the force F will see its coast line widen at the level of the skate. It follows a reduction in the radius of curvature of the turn, favorable to the practice of special slalom.

As is known, a pair of skis (see FIG. 9) comprises two skis, respectively the left designated by the general reference (G) and the right designated by the reference (D). These skis are symmetrical with respect to a plane M passing between them. According to the invention, the inclined characteristic bands (25) descend from left to right on the left ski G1 and rise from left to right on the right ski D, so that the directions of the two reinforcing bands (25) are cross on the M plane, below the skis. Thus, when the skier has to make long radius turns, he exerts a minimum load on his skis and he inscribes them in curves resulting from the original dimension line, without significant modifications. However, to make more turns tight, the skier's pulse becomes more energetic, so the load F increases by varying the dimension line which, in this case, will widen even more on the inner edge to register curves of smaller radii. Thus, the ski according to the invention has become interactive, since it is modified according to need.

FIG. 10 illustrates a ski according to the invention in which the reinforcing bands (50-53) are inclined at a constant angle and are arranged in pairs on either side of the neutral fiber FN.

FIG. 11 shows another variant of the invention in which the entire intermediate space (60) provides the inclined reinforcement function. This space (60) is occupied by an asymmetrical reinforcement core with respect to the plane P of symmetry of the lower assembly, that is to say of which the fibers which form reinforcement have an inclination α. This core can be made of wood with its inclined fibers or of glued laminated wood, so that the lamellar stack of fibers is inclined by this value α.

FIG. 12 shows a ski of particular shape in which the reinforcing strip (70) asymmetrical to the plane (P) is glued against the shell (26), inside the intermediate space (20) filled with polyurethane foam .

Claims (8)

1 / Ski including: . a first lower assembly (10), comprising a flat sole (11) having a plane of symmetry P perpendicular to the plane of the sole and passing through its median longitudinal axis I-I ', . a second upper assembly (15) forming a top (16) and side edges (17,18), . these two assemblies defining an intermediate space (20), in which the neutral fiber (FN) is located and in which, at least at the level of the shoe (2) is disposed a longitudinal main reinforcement element inclined relative to the plane of the sole (12), characterized in that the inclined longitudinal reinforcing element consists of a flat strip (25) which, while defining an acute angle with respect to the plane of the sole (11), is arranged asymmetrically with respect to the plane (P) of symmetry of the lower assembly (10). 2 / Ski according to claim 1, characterized in that it comprises a single straight flat strip (25) of reinforcement extending from the first lower assembly (10) towards the second upper assembly (15), cutting the plane P and by defining two portions of the same width, arranged on either side of this plane P. 3 / Ski according to claim 2, characterized in that the characteristic reinforcing flat strip (25) extends from the tip (1) to the heel (3), and in that the inclination of this strip (25 ) varies gradually and continuously from the tip (1) to the heel (3), respectively from zero degree at the tip (1) and at the heel (3), to 45 ° at the level of the shoe (2) . 4 / Ski according to one of claims 1 and 2, characterized in that the inclination of the strip (25) relative to the plane of the sole (11) is constant and is close to 45 ° over the entire length of the ski . 5 / Ski according to claim 1, characterized in that it comprises several bands (30,31,50,51,52,53) parallel. 6 / Ski according to one of claims 1 to 5, characterized in that the intermediate space (20) is filled with a plastic foam. 7 / Ski according to one of claims 1 to 5, characterized in that the flat longitudinal reinforcing strip (40) inclined is inserted in a neutral core (35), itself embedded in the intermediate space (20). 8 / Ski according to one of claims 1 to 6, characterized in that the inclined flat strip (25) is constituted by a reinforcing core (60) of wood whose lamellar fibers are inclined relative to the plane P.

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