EP0470347B1 - Variable convexe of the upper ski surface - Google Patents

Abstract

The ski according to the invention comprises an upper surface (6) which has, in transverse section, over at least the greater part of the length of the ski, a convex rounded shape. The average radius (RM) of the upper surface (6) varies as a function of the longitudinal position of the transverse section in question along the ski, and is smaller in the central zone of the ski than in the vicinity of the tip and heel of the ski. This makes it possible to increase the height in the central zone of the ski whilst reducing the height of the edges of the ski. <IMAGE>

Description

The present invention relates to skis used in winter sports, and intended to slide on snow and ice.

The skis generally used have a lower sliding face connecting to two lateral faces along two lower edges provided with metal edges, the lateral faces connecting to an upper face. The skis have a relatively small width compared to their length, their anterior end being curved upwards to form a spatula. The thickness of the ski is generally greater in the central part than in the front and rear parts of the ski. In the most generally used conventional forms, the width of the lower face of the ski is smaller in the central part than in the rear and front parts, the width being maximum in the front part of the ski, that is to say at the neighborhood of the spatula.

In known ski structures, the upper face of the ski is generally a ruled surface, that is to say defined by the longitudinal displacement of a straight transverse line parallel to the lower face of the ski. In other words, the cross section of the ski is generally a rectangle or a trapezoid, the large opposite sides of the rectangle or the trapezium being formed by the lower face and the upper face of the ski, the small opposite sides of the rectangle or the trapezoid being formed by the side faces of the ski.

The greater thickness of the ski in the central zone gives this central zone increased rigidity. This central zone is also intended to receive the bindings for the adaptation of a user's shoe. On the other hand, the front and rear areas of the ski, which have a reduced thickness, are more flexible and elastically deform when the ski is used. If one wishes to make a ski having good flexibility in the anterior and posterior zones, it is therefore necessary to provide such anterior and posterior zones having a reduced thickness.

A first problem encountered in traditional ski structures is that the central zone of the ski, which has a relatively large thickness to give it great rigidity, causes a fairly appreciable increase in the weight of the ski.

A second problem encountered in known ski structures is that the necessary thickness of the ski, to obtain sufficient mechanical strength, leads to having ski side faces having a relatively large height. This relatively large height of the lateral faces gives the ski a relatively heavy appearance, and constitutes a lateral bearing surface of large surface opposing the lateral penetration of the ski into the snow, thus slowing the lateral movements of the ski when cornering or in skid.

Another problem encountered in known ski structures is that the central part of the ski has a relatively reduced width compared to the end parts of the ski, so that the ski boot adapted to the bindings in the central zone of the ski generally extends on both sides of the ski. As a result, when driving a turn, the ski and the boot being inclined with respect to the ground, the edge of the boot inside the turn is brought closer to the ground and tends to touch it, which risks slowing down the progression. of the skier and disturb the effectiveness of the support on edges.

Document FR-A-2 565 836 relates to a one-piece ski structure which comprises a reinforced box with biconvex profile supported on a pair of edges. Such a shape makes the structure sensitive to various stresses (flexion, torsion, vertical compression, microdeformations ...).

The present invention proposes to remedy the aforementioned drawbacks by the design of a new form of ski. The shape of the ski is progressive as a function of the longitudinal portion considered along the ski, and this progressive shape is such that the ski can be given an increased real height while decreasing the height of the edges or side faces of the ski, giving in skiing the appearance of a thinner ski, and favoring the lateral penetration of the ski in the snow.

The progressive shape of the ski according to the invention is such that the end regions of the ski can be given increased flexibility simultaneously without excessively reducing the height of the edges of the ski in said end zones, so as to maintain resistance. sufficient mechanics of the part supporting the lower edges of the ski.

Simultaneously, the ski structure according to the invention has the effect of raising the boot support zone relative to the lower sliding surface of the ski, favoring the release of the boot sole from the ground when driving the turns, without increasing the volume and weight of the ski compared to a traditional structure with rectangular or trapezoidal section.

In certain embodiments, it is also possible to take advantage of the particular external shape of the ski according to the invention, to give the ski properties of increased mechanical resistance in bending in the central zone, and / or properties of increased mechanical resistance in torsion over the entire length of the ski, without increasing the volume and the weight of the ski compared to a traditional structure with rectangular or trapezoidal section.

• la face supérieure présente, en coupe transversale, sur au moins la plus grande partie de la longueur du ski, une forme convexe,
• ladite forme convexe de coupe transversale de face supérieure est identique à ou peu différente d'un cercle passant par la partie centrale et les extrémités de la forme convexe, le rayon du cercle définissant le rayon moyen RM de ladite coupe transversale,
• ledit rayon moyen RM de coupe transversale de face supérieure varie en fonction de la position longitudinale de coupe transversale considérée le long du ski,
• ledit rayon moyen RM prend dans la zone centrale de ski des valeurs inférieures aux valeurs dudit rayon moyen RM dans l'une au moins des zones d'extrémité antérieure et postérieure du ski.

To achieve these and other objects, the ski according to the invention is such that:

• the upper face has, in cross section, over at least the greatest part of the length of the ski, a convex shape,
• said convex shape of transverse cross section on the upper face is identical to or little different from a circle passing through the central part and the ends of the convex shape, the radius of the circle defining the mean radius RM of said transverse section,
• said mean radius RM of cross section of the upper face varies as a function of the longitudinal position of cross section considered along the ski,
• said average radius RM takes on values in the central ski area values smaller than the values of said average radius RM in at least one of the front and rear end zones of the ski.

According to an advantageous embodiment, the ski comprises, over most of its length, an upper blade of mechanical resistance arranged in the vicinity of the upper face of the ski in its median zone close to the vertical longitudinal median plane of the ski, so that the distance between the said upper blade and the plane of the neutral horizontal fibers of the ski varies as a function of the mean radius RM of the upper face of the ski, and the said blade is thus further from the plane of the neutral fibers in the zones with a small mean radius RM, and is closer to the plane of the neutral fibers in the zones with a larger medium radius RM.

According to another embodiment, the ski comprises a box structure, formed of a central core surrounded by a tubular element of mechanical resistance, the tubular element having an external surface close to the external surface of the ski and substantially parallel to this, so that the cross section of the tubular element is rounded to follow the convex shape of the upper face of the ski, giving the tubular element better torsional rigidity.

• la figure 1 est une vue schématique de dessus d'un ski selon la présente invention ;
• la figure 2 est une vue schématique de côté d'un ski selon la présente invention, les dimensions et déformations dans le sens de l'épaisseur du ski ayant été volontairement représentées à plus grande échelle que la longueur du ski, dans un but de compréhension de l'invention ;
• les figures 3 à 5 représentent respectivement la silhouette des coupes transversales du ski selon la présente invention selon les plans A-A, B-B, C-C mentionnnés sur les figures 1 et 2 ;
• la figure 6 représente schématiquement une coupe transversale d'un ski traditionnel à section rectangulaire muni d'une lame supérieure de résistance mécanique ;
• la figure 7 illustre schématiquement une structure de ski selon l'invention, en coupe transversale montrant une lame de résistance mécanique supérieure ;
• la figure 8 est une coupe schématique transversale d'un ski selon un mode de réalisation avantageux de l'invention ; et
• la figure 9 illustre les variations de courbures de face supérieure d'un ski selon un mode de réalisation de l'invention, dans les zones antérieure, centrale et postérieure du ski.

Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, among which:

• Figure 1 is a schematic top view of a ski according to the present invention;
• Figure 2 is a schematic side view of a ski according to the present invention, the dimensions and deformations in the thickness direction of the ski having been voluntarily shown on a larger scale than the length of the ski, for the purpose of understanding of the invention;
• Figures 3 to 5 show respectively the silhouette of the cross sections of the ski according to the present invention according to the plans AA, BB, CC mentioned in Figures 1 and 2;
• FIG. 6 schematically represents a cross section of a traditional ski with rectangular section provided with an upper blade of mechanical resistance;
• Figure 7 schematically illustrates a ski structure according to the invention, in cross section showing a blade of higher mechanical strength;
• Figure 8 is a schematic cross section of a ski according to an advantageous embodiment of the invention; and
• FIG. 9 illustrates the variations in curvature of the upper face of a ski according to an embodiment of the invention, in the front, central and rear areas of the ski.

As shown in the figures, the ski according to the invention comprises a lower sliding face 1 connecting to two lateral faces 2 and 3 according to two respective lower edges 4 and 5 provided with metal edges. The lateral faces 2 and 3 are connected to an upper face 6. The front end of the ski is bent upwards to form a spatula 7. The rear end of the ski is slightly bent upwards to form the heel 8. The ski may in particular comprise a tip tip 7 and a heel protector 8, fixed by any means such as snap-fastening, bonding or the like.

The lateral faces 2 and 3 of the ski, in the embodiment shown in FIGS. 3 to 5, are inclined relative to the perpendicular to the lower face 1 of the ski, at a substantially constant angle A. In the embodiment shown in the Figures 7 and 8, the side faces 2 and 3 of the ski are substantially perpendicular to the underside 1. In reality, in a ski according to the invention, one can choose an angle A close to zero degrees as in the embodiment of the Figures 7 and 8, or an angle A close to five degrees and constant as in the embodiment of Figures 3 to 5, or an angle A whose value is variable depending on the longitudinal position considered along the ski. For example, the angle A can be greater in the vicinity of the ends of the ski, on the sections AA of FIG. 3 or CC of FIG. 5, than in the central zone of the ski on the section BB of FIG. 4.

The lateral faces 2 and 3 of the ski are connected to the upper face 6 by upper lateral edges 9 and 10 with rounded cross section of radius RL. The radius RL advantageously has a value less than 6 millimeters.

The upper face 6 of the ski according to the invention has, in cross section, over at least the greatest part of the length of the ski, a convex shape, for example rounded. This convex cross-sectional shape of the upper face 6 of the ski is an upper line, the central part of which forms an apex and the two ends of which are inclined at an angle of less than about 60 degrees relative to the lower face of the ski. Said upper line has a shape identical to or slightly different from a circle, that is to say that it deviates relatively little from the circle passing through said vertex and said ends. Said circle which most closely approximates the convex cross-sectional shape of the upper face of the ski has a radius called the average radius RM of cross-section.

The average radius RM of cross section varies as a function of the longitudinal position of cross section considered along the ski. The values that the average radius RM takes in the central zone of the ski are lower than the values that the average radius RM takes in at least one of the front or rear end zones of the ski.

In the embodiments which have been shown in the figures, the convex cross-sectional shape of the upper ski face is substantially identical to a circle, that is to say that its curvature is substantially constant over the entire width of the cross section. This embodiment confers a certain regularity on the upper surface.

However, the invention also applies to other convex shapes of cross section of the upper face. For example, one can define an upper face of more elliptical shape, with a central part whose curvature is less than the curvature of the lateral zones of the upper face. However, it must be avoided that the curvature of the lateral zones of the upper face is too great, because it then approaches a rectangle, and the advantages of the invention are lost.

It is also possible to design an upper face of the ski, the cross section of which is a polygonal line close to the circle of average radius RM, for example a line with three segments, with a central segment substantially parallel to the underside of the ski and two inclined lateral segments. .

In all cases, whether it is an elliptical line, a polygonal line or any other shape, said convex shape of cross section of the upper ski face must remain little different from a circle passing through its central part and its ends.

In the advantageous embodiment represented in FIGS. 3 to 5, the values which the average radius RM takes in the central zone of the ski, represented in FIG. 4, are less than the values of said average radius RM in the anterior end zone of the ski, represented in FIG. 3, and are smaller than the values taken by said mean radius RM in the rear end region of the ski, represented in FIG. 5. Also, the maximum average radius REA in the anterior end zone of the ski is advantageously greater than the maximum average radius REP in the rear end region of the ski.

As an alternative, to search for other effects, it could be provided that the maximum average radius REA in the anterior end region of the ski is less than the maximum average radius REP in the rear region of the ski.

The ski bindings, intended to secure a ski boot on the upper face 6 of the ski, are generally arranged in the central area of the ski or a little behind the middle of the ski in the area shown in FIGS. 1 and 2 between the cross sections FF and GG. Depending on the case, and in particular depending on the size of the user's ski boots, the bindings are fixed on the upper face of the ski in longitudinal positions which can differ from one case to another, and which lie in an area between 40 and 60 cm in length. To facilitate the positioning of the bindings on the upper face of the ski, it is advantageously possible to provide for the mean radius RM of cross section to keep a substantially constant value RC throughout the central area lying between the planes FF and GG. Bindings can thus be provided, the lower support face of which is shaped to apply exactly to the upper ski face, whatever the longitudinal position in the central zone intended to receive the bindings.

• le rayon moyen RM dans la zone centrale du ski soit compris entre 70 et 90 millimètres environ ;
• le rayon moyen maximum REA dans la zone antérieure du ski soit compris entre 120 et 155 millimètres environ ;
• le rayon moyen maximum REP dans la zone postérieure du ski soit compris entre 108 et 138 millimètres environ.

Advantageously, it is possible to provide a curvature of the upper face of the ski such that:

• the average radius RM in the central area of the ski is between 70 and 90 millimeters approximately;
• the maximum average radius REA in the anterior zone of the ski is between approximately 120 and 155 millimeters;
• the maximum average radius REP in the rear region of the ski is between approximately 108 and 138 millimeters.

FIG. 9 illustrates the variations in average radius RM, or curvature, of the cross section of the upper face of the ski as a function of the longitudinal position of the cross section considered. The curve 20 represents the transverse profile of the upper ski face in the central area of the ski. In this central zone, the curvature is constant, and, to follow the variations in width of the ski, the curve stops at the ends 21 and 22 in the narrowest part of the ski, and extends to the ends 23 and 24 in the cross sections of the central ski part closer to the ends of the ski. The curve 30 represents the transverse profile of the upper ski face in the heel area. Curve 40 represents the transverse profile of the upper ski face in the tip region.

Preferably, to avoid discontinuities in shape, the mean radius RM of the upper face 6 of the ski varies continuously as a function of the longitudinal position of transverse section considered along the ski, from the value RC in the central area of the ski, up to maximum REA and REP in the anterior and posterior ski areas.

The average radius RM of the upper ski face varies as a function of the longitudinal position of the cross section considered, because to obtain the desired flexibility, the thickness of the ski must decrease the closer you get to the ends. And, as the ski widens at the same time, the upper face 6 must be flattened more and more in a progressive manner, to avoid reducing the height of the edges too much in the vicinity of the ends. As a result, it is advantageous to continuously increase the value of the average radius RM when one approaches the ends.

Thanks to the convex rounded shape of the upper ski face 6, in particular in the central ski area shown in FIG. 4, it can be understood that a relatively large ski height H1 and a relatively small ski height H2 are obtained. low, for the same ski cross section, compared to the constant height H obtained in the case of a ski with rectangular section as shown in FIG. 6. Thus, compared to a traditional ski with rectangular section, for a same section and therefore the same weight, the ski according to the present invention makes it possible to increase the height H1 or distance of the sole of the shoe relative to the ground, and makes it possible simultaneously to decrease the height H2 of the edges or lateral faces 2 and 3 of the ski.

According to the invention, it is advantageous to take advantage of the particular convex shape of the upper face 6 of the ski in order to adapt particular means of internal structure of the ski giving the ski increased rigidity.

For example, in FIG. 7, the internal structure of the ski comprises an upper blade of mechanical strength 11, of thickness E1 and of width B1, disposed near the upper face 6 of the ski. The upper blade of mechanical strength 11 has the effect of giving the ski sufficient rigidity to correctly oppose the flexing of the ski in the longitudinal direction. When bending, the ski reacts like a beam and forms an arc, the fibers located towards the inside of the arc tending to shorten, the fibers located towards the outside of the arc tending to lengthen , and one can define a mean plane 12 containing the neutral fibers, that is to say the fibers whose length is not significantly modified during bending. The stiffening effect obtained by the upper blade of mechanical strength 11 naturally depends on the thickness E1 and the width B1 of the blade, as well as on the nature of the material used to form this blade, but also depends very significantly on the average distance 0.5 x (Y1 + Z1) between this strip 11 and the plane 12 of the neutral fibers. The rigidity obtained is thus greatly increased when the distance Y1 between said blade 11 and the plane 12 of the neutral fibers is increased.

In the case of the present invention, the convex shape of the upper face 6 of the ski makes it possible to arrange the upper blade of mechanical resistance 11 at an average distance 0.5 x (Y1 + Z1) greater than the average distance 0, 5 x (Y + Z) possible in a structure with rectangular section as shown in FIG. 6. Thanks to this increase in distance, the invention makes it possible to significantly reduce the thickness E1 and the width B1, and therefore the volume and the weight of the upper blade of mechanical strength 11 for equivalent performance compared to a traditional structure with rectangular section of thickness E and width B. It is possible, for example, to provide an upper blade of mechanical strength 11 whose width B1 is less than the width B of the blade required in a traditional structure with rectangular section, for the same thicknesses E1 and E. It follows that the total weight of the ski according to the present invention can be less than the weight of a traditional ski with rectangular or trapezoidal section.

In the embodiment of FIG. 8, the particular shape of the ski according to the invention is used to increase its torsional rigidity. In this case, the ski comprises a box structure, formed of a central core 13 surrounded by a tubular element 14 of mechanical strength. The tubular element 14 has an outer surface which is close to the outer surface of the ski and substantially parallel thereto, or which can constitute the outer surface of the ski itself. In this way, the cross section of the tubular element is convex, for example rounded convex at least in the portion corresponding to the upper face 6 of the ski, so that the general section of the tubular element approaches a section circular, giving the tubular element better torsional rigidity.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below.

Claims (13)

1. Ski for maneuvering on the snow, comprising a lower gliding surface (1) joining at two lateral surfaces (2, 3) along two bottom edges (4, 5), the lateral surfaces (2, 3) joining at an upper surface (6);

   - the upper surface (6), in a transverse section, having a convex shape on at least the largest portion of the length of the ski,

   - said convex shape of the transverse section of the upper surface being identical to or slightly different from a circle passing through the central portion and the ends of the convex shape, the radius of the circle defining the average radius RM of said transverse section, characterized in that;

   - said radius RM of the transverse section of the upper surface (6) varies as a function of the longitudinal position of the transverse section considered along the ski and,

   - in the central zone of the ski, said radius RM has values less than the values of said average radius RM in at least one of the front and rear end zones of the ski.
2. Ski according to claim 1, characterized in that the average radius RM in the central zone of the ski is substantially equal to a constant value RC in the portion of the central zone (F-F ; G-G) intended to receive the bindings.
3. Ski according to claim 2, characterized in that the portion of the central zone in which the average radius RM is substantially equal to the constant value RC, has a length comprised between 40 and 60 centimeters.
4. Ski according to any of claims 1 to 3, characterized in that the values of the average radius RM in the central zone are less than the values of said average radius RM in the front end zone of the ski, and than the values of said average radius RM in the rear end zone of the ski.
5. Ski according to claim 4, characterized in that the maximum average radius REA in the front end zone of the ski is greater than the maximum average radius REP in the rear end zone of the ski.
6. Ski according to claim 4, characterized in that the maximum average radius REA in the front end zone of the ski is less than the maximum average radius REP in the rear end zone of the ski.
7. Ski according to any of claims 1 to 5, characterized in that the substantially constant value RC of the average radius RM in the central zone of the ski is comprised between 70 and 90 millimeters.
8. Ski according to any of claims 1 to 7, characterized in that the maximum value REA of the average radius in the front zone of the ski is comprised between 120 and 155 millimeters.
9. Ski according to any of claims 1 to 8, characterized in that the maximum value REP of the average radius in the rear zone of the ski is comprises between 108 and 138 millimeters.
10. Ski according to any of claims 1 to 9, characterized in that the average radius RM of the upper surface (6) of the ski varies continuously as a function of the longitudinal position of the transverse section considered along the ski.
11. Ski according to any of claims 1 to 10, characterized in that the rounded upper surface (6) is joined to the lateral surfaces (2, 3) by the upper lateral edges (9, 10) having a rounded transverse section with a radius RL less than 6 millimeters.
12. Ski according to any of claims 1 to 11, characterized in that it comprises, along the largest portion of its length, an upper mechanical resistance blade (11) arranged in the vicinity of the upper surface (6) of the ski in its median zone close to the median longitudinal vertical plane of the ski, such that the distance between said upper blade (11) and the plane (12) of the horizontal neutral fibers of the ski varies as a function of the average radius RM of the upper surface (6) of the ski, and said blade (11) is thus at a greater distance from the plane (12) of the neutral, fibers in the zones having a small average radius RM, and is closer to the plane (12) of the neutral fibers in the zones having a larger average radius RM.
13. Ski according to any of claims 1 to 11, characterized in that it comprises a box type structure, formed of a central core (13) surrounded by a tubular element (14) of mechanical resistance, the tubular element having an outer surface close to the outer surface of the ski and substantially parallel thereto, such that the transverse section of the tubular element (14) is rounded in order to follow the convex shape of the upper surface (6) of the ski, conferring an improved torsional rigidity to the tubular element (14).

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