EP1430935A1 - Alpine ski - Google Patents

Abstract

The alpine ski has a line dimension (9) with a radius less than 24 meters. The front (10) and/or rear (18) ends have a cavity (11,15) emerging longitudinally. The dimensions of the cavity enable the deformation of the end when a transverse force is exerted on the front or rear lines of contact so as to enable the bringing together of the ski internal and external edges.

Description

Technical area

The invention relates to the field of sliding sports, and more specifically to that of the manufacture of alpine skis, that is to say generally of skis allowing you to descend slopes by making turns. It aims more particularly a ski of a new design presenting a line of coast variable depending on the load.

Previous techniques

In general, an alpine ski has several deformation capacities. Thus, one can determine a stiffness in longitudinal bending, corresponding to the ability of the ski to bend when it receives a vertical force. This bending is used especially when the ski has to follow the slopes of the slopes, as well as turning course.

A ski also has a torsional stiffness, corresponding to its capacity deformation when it undergoes a torque applied along a substantially axis parallel to skiing. This bending capacity allows slight twisting of the ends ski.

In addition, a ski has a stiffness in lateral bending, corresponding to its deformation capacity when it receives a lateral force. This stiffness in bending side is particularly reduced on existing skis, taking into account that the width of a ski is much greater than its thickness.

To date, there is a marked tendency to make skis whose line the coast is particularly dug and whose length is reduced. This line of rib draws on each side of the ski a curve similar to an arc, the radius of curvature is frequently less than approximately 24 meters. In a way general, we define the radius of curvature of this coast line by the radius of the circle passing through three points which are the two points of maximum width in tip and heel, as well as the point of minimum width at the level of the skate.

This dug coast line allows in the practice known as "cut turns" or "carving" to register the ski in a turn with a determined radius, therefore depending on the radius of curvature of this coast line, minimizing the skid effects.

This carving practice requires that the skier lean sideways from very important and that he exerts high efforts during the turn to inscribe the edge line as much as possible in the snow. Such turns induce therefore a high speed, and are therefore not within the reach of an average skier.

If the speed and the force exerted by the skier on the edge are insufficient, the edges fit into the snow only at the two width points maximum of the coast line, as well as possibly over a small part of the sideline. Outside these areas, the dimension line is in a situation of skid. We can see that driving the turn is therefore not really optimal.

An objective of the invention is to allow the edge to be hooked onto a most of the coast line, regardless of the radius of curvature of the turn, the inclination of the ski in relation to the snow, and the speed of the skier.

In the past, we have already proposed to make skis according to architectures particular, favoring the longitudinal bending of certain parts of the board, and in particular the ends. In document AT 23 80 74, for example, a ski whose front part is split, so that each of these parts can be move vertically independently of each other. This arrangement allows reduce the stiffness in longitudinal bending of each end of the ski. However, the coast line of such a ski remains constant, and in this case rectilinear. Thus, as mentioned above, when the ski is entered in the turn, only a very limited area of the edge catches the snow, the rest of the coast line slip, or not in contact with snow.

A similar approach was also proposed in the document DE 34 44 345. The board described in this document has a slot extending longitudinally from the tip to the heel, to allow decrease in overall torsional stiffness. This board also has a reduced longitudinal bending stiffness, since when the ski is tilted laterally to the snow, only half of the board comes into contact snow, and therefore has a useful stiffness.

A similar goal was also sought in the production of the ski described in document FR 2 227 883.

Also described in document FR 2794374 is a ski having a longitudinal slit opening at the end of the tip or heel. Means are provided to modify the difference between the two portions separated by the slot, and therefore to modify the dimension line of the ski before its use, according to the abilities of the skier and the type of ski he practices.

EP 1 297 869 has also described a ski having a mechanical device placed inside a housing formed inside the ski. This device is intended to increase the spacing between the left and right edges when the ski flexes.

Statement of the invention

The invention therefore relates to an alpine ski, having a sunken coast line, that is to say which has a radius less than about 24 meters. Like skiing described in document FR 2794374, the front and / or rear ends have a recess opening longitudinally at this end.

According to the invention, this ski is characterized in that the dimensions of this recess allow the deformation of this end when a lateral force is exerted at the front and / or rear contact lines, so as to allow the approximation of the left and right ski edges. It will be noted that under real conditions, forces are exerted on the ski not only laterally, but also vertically, or more generally perpendicular to the upper surface of the ski. In this way, the deformation observed on snow is generally such that the vertical stresses cause a displacement which results in a separation of the right and left edges. However, the horizontal component (or more precisely parallel to the sole) of the forces undergone results in a bringing together of the right and left edges, in projection in the plane of the sole of the ski.

In other words, the invention consists in separating the end of the ski into two parts therefore having less stiffness in lateral bending, so that these parts which are free can therefore each approach the median longitudinal plane of the skiing when a stress is exerted transversely. The dimensions of the recess are such that they allow the displacement of the two portions of the end. In this way, the coast line of the ski can deform as a function only from the track topology, but also from the efforts exerted by the skier. When the ski is tilted on the edge, the contact points extremes with snow are close to the maximum width points of the ski, which are themselves neighbors of the front and rear contact lines, defined so normalized.

• le ski est disposé sur le coté avec sa semelle de glisse verticale ;
• le ski est maintenu bloqué au niveau d'un point fixe avant situé à une distance de 3/10 de la longueur totale L_n du ski, à partir de l'extrémité avant du ski;
• une force F_av est exercée verticalement sur le chant du ski, au niveau d'un point d'application situé à une distance de 120 millimètres de l'extrémité avant du ski, ledit point d'application étant donc situé à une distance L_av = 0,3 x L_n - 120, mesurée en millimètres, du point fixe avant ;
• le point d'application subit un déplacement vertical Y_av.

It has been determined that in order to obtain the desired deformation effect, the ski should be made so as to give it specific mechanical properties of stiffness. Thus, with regard to the front end, the report: VS BC = Y BC F BC · The 3 BC must be greater than 0.3.10 ^-9 , in which L _av , and Y _av , expressed in millimeters, and F _av expressed in Newtons, are determined during the measurement in lateral flexion of the front part of the ski, measurement during which:

• the ski is placed on the side with its vertical gliding sole;
• the ski is kept locked at a front fixed point located at a distance of 3/10 of the total length L _n of the ski, from the front end of the ski;
• a force F _av is exerted vertically on the edge of the ski, at a point of application located at a distance of 120 millimeters from the front end of the ski, said point of application being therefore located at a distance L _av = 0.3 x L _n - 120, measured in millimeters, from the front fixed point;
• the point of application undergoes a vertical displacement Y _av .

• le ski est disposé sur le coté avec sa semelle de glisse verticale ;
• le ski est maintenu bloqué au niveau d'un point fixe arrière situé à une distance de 3/10 de la longueur totale L_n du ski, à partir de l'extrémité arrière du ski ;
• une force F_ar est exercée verticalement sur le chant du ski, au niveau d'un point d'application situé à une distance de 50 millimètres de l'extrémité arrière du ski, ledit point d'application étant situé à une distance L_ar = 0,3 x L_n - 50, mesurée en millimètres, du point fixe arrière ;
• le point d'application subit un déplacement vertical Y_ar.

Similarly, with regard to the rear end, the ratio: VS ar = Y ar F ar · The 3 ar must be greater than 0.3.10 ^-9 , in which L _ar , and Y _ar , expressed in millimeters, and F _ar expressed in Newtons are determined during the measurement in lateral flexion of the rear part of the ski, measurement during which:

• the ski is arranged on the side with its vertical gliding sole;
• the ski is kept blocked at a rear fixed point located at a distance of 3/10 of the total length L _n of the ski, from the rear end of the ski;
• a force F _ar is exerted vertically on the edge of the ski, at a point of application located at a distance of 50 millimeters from the rear end of the ski, said point of application being located at a distance L _ar = 0.3 x L _n - 50, measured in millimeters, from the rear fixed point;
• the point of application undergoes a vertical displacement Y _ar .

In practice, the ski can advantageously be formed of two beams longitudinal arranged side by side, associated at the level of the skate area. In this case, the front or rear ends of these two beams are sufficiently spaced to form the zone of the recess which opens longitudinally, and allows therefore the transverse bringing together of the two beams under stress.

Advantageously in practice, these two beams can be combined by a mounting platform for the binding.

The invention also covers variants in which the ski is not made from two separate beams, but only one beam whose skate area is monolithic, and which then presents either at the front level or at the rear level, either at these two levels, two separate separate branches to form the recess feature.

In practice, the recess must allow a certain deformation under stress lateral. This recess therefore corresponds to a modification of the structure of the board at the end considered, and can be made of different ways.

Thus, this recess can be in the form of a total absence of material. This recess can also be filled with a material of filling which is elastic and flexible, and which therefore allows the approximation of each of the parts defining the recess in the direction of the longitudinal plane ski median.

This filling makes it possible in particular to avoid the passage of snow through the recess.
In another embodiment, this recess can be delimited at the lower level by a deformable layer, constituting the gliding sole and therefore connecting the two parts defining the recess.

In other words, the gliding sole can be continuous over the entire width of the ski, and therefore plug the underside of the recess, so as to prevent snow intrusion. This sole remains very easily deformable under stress transverse due to its low stiffness. However, the volume above the layer forming the sole, at the level of the characteristic recess, is therefore either free of material, or filled with an easily deformable material.

Brief description of the figures

La figure 1 est une vue de dessus d'un ski conforme à l'invention.

Les figures 2 et 3 sont des vues de dessus du ski de la figure 1, montrant la déformation latérale de l'extrémité respectivement avant et arrière.

La figure 4 est une vue en perspective sommaire du ski de la figure 1, montré dans une situation où le ski est sollicité, dans un virage à droite.

La figure 5 est une section sensiblement au niveau de la ligne de contact avant du ski de la figure 4.

Les figures 6 à 8 sont des vues en coupe sensiblement au niveau de la ligne de contact avant de trois variantes de réalisations.

The manner of carrying out the invention as well as the advantages which result therefrom will emerge clearly from the description of the embodiment which follows, in support of the appended figures in which:

Figure 1 is a top view of a ski according to the invention.

Figures 2 and 3 are top views of the ski of Figure 1, showing the lateral deformation of the front and rear end respectively.

Figure 4 is a summary perspective view of the ski of Figure 1, shown in a situation where the ski is stressed, in a right turn.

FIG. 5 is a section substantially at the level of the front contact line of the ski of FIG. 4.

Figures 6 to 8 are sectional views substantially at the level of the front contact line of three alternative embodiments.

Way of realizing the invention

As already mentioned, the invention relates to an alpine ski (1), which can be produced according to the embodiment illustrated in FIG. 1. In this case, the ski (1) is composed of two beams (2, 3), substantially symmetrical around the plane longitudinal median of the ski (4).

These two beams (2, 3) are connected by a raising platform (5) fixing.

According to the invention, the ski has a recess (11), opening out (12) at the front end of the ski (10). Likewise at the rear level, skiing (1) has a recess (15) formed by the divergent portions (16, 17) of the beams (2, 3). This recess (15) opens at the rear (18) of the ski (1).

In this way, the ski has a capacity for deformation under stress side which is illustrated in Figures 2 and 3, respectively at the front and back of the ski.

This deformation can be measured by a stiffness test in lateral bending, which is illustrated in figure 2.

Thus, in this case, the ski is arranged on the side with its vertical gliding sole. The ski (1) is kept blocked at a front fixed point (20), located at a distance D _AV of 3/10 ^th of total length L _n of the ski, measured from the front end (10) ski.

A force F _AV is exerted vertically on the edge of the ski, at a point of application (21), located at a distance d _AV of 120 millimeters from the front end (10) of the ski (1). This point of application is therefore located at a distance L _AV of 0.3 x L _n - d _AV from the front fixed point (20).

The displacement Y _AV is then measured in the vertical direction of the point of application (21) of the force F. In the case where the curve giving the displacement observed as a function of the force exerted is not completely linear, in particular in the zone corresponding to the low forces, the forces and displacement are then measured in a differential manner, in a linear portion of this curve.

Good results in snow behavior have been observed when the lateral stiffness in flexion, defined by the criterion C _av = Y _av / F _av · L ³ _av , is greater than 0.3.10 ^-9 , with Y _av and L _av expressed in millimeters, and F _av expressed in Newtons. In practice, this criterion value can be greater than 1.10 ^-9 , or even 1.2.10 ^-9 .

The same type of measurement can be made at the rear end, as shown in figure 3.

In this case, the ski is also kept blocked at a fixed point located at a distance D _AR equal to 3/10 ^th of the total length L _n of the ski, measured from the rear end (8) of the ski.

A force F _ar is exerted vertically on the edge of the ski, at an application point (25) located at a distance of 50 millimeters from the rear end (8) of the ski. The point of application (25) is therefore located at a distance L _ar = 0.3 x L _n - d _AR , from the rear fixed point (24). The vertical displacement Y _ar of the point of application (25) of the force F _ar is also measured.

In practice, good results have been obtained with regard to the stiffness in lateral bending when the criterion C _ar = Y _ar / F _ar · L ³ _ar is greater than 0.3.10 ^-9 , with Y _ar and L _ar expressed in millimeters, and F _ar expressed in Newtons. This criterion can even be increased beyond 1.10 ^-9 , or even 1.5.10 ^-9 , depending on the flexibility desired.

Thus, we observe that the lateral deformation of the ski is particularly important, and unrelated to existing skis, for which the same criteria are close to 0.15.

When the force exerted, whether at the front or at the rear, is of the order of 100 Newtons, the ratio of the displacement Y over the total length L _n of the ski is greater than 0.0015. This means in practice that the deformation can reach practically 1 centimeter at the front and rear ends.

In practice, this significant bending under lateral stress results in as illustrated in FIG. 4 by the fact that the ski (1) can have a line of coast (9) evolving according to the stress. Thus, in the case illustrated in Figure 4 which is exaggerated as regards the deformations to facilitate the understanding, we observe that the beam (3) is relatively deformed, having close to the median longitudinal plane (4) of the ski, so that the line of edges (19) in contact with snow have a greatly increased radius of curvature. We observe that most of the edge of the beam (3) comes into contact with the snow, with the exception of the tip forming the raised spatula. This edge therefore comes hang snow over a large part of its length, and therefore allows safer cornering. This characteristic deformation can be obtained that the angle of inclination of the ski with respect to the snow, that is to say as a function the slope of the piste and the position of the skier.

As illustrated in Figure 5, this deformation results first of all in a approximation of the beam (3) towards the median longitudinal plane (4). On the Figure 5, the dotted shape (3 ') represents the beam (3) in a configuration symmetrical of the beam (2) with respect to the median longitudinal plane (4), in a situation where it is not requested. The distance E separating the two beams in a horizontal plane is therefore less than the distance E 'corresponding to the situation in which the beam is not stressed. Likewise, the edge (19) therefore shifts compared to the position (19 ') that it would occupy without stress. The beam (3) is also deforms in a longitudinal bending direction, while the beam (2) does not hardly deforms. So the two beams, which are not all two in contact with the snow surface, offset one with respect to the other. More specifically, the beam (3) coming into contact with the snow shifts towards the top of a distance D, in a direction perpendicular to the plane of the sole.

We realized that the stiffness in longitudinal bending of each beam (measured with the ski flat on its sole, and receiving a load perpendicular to its sole) must correspond substantially to that of a traditional ski, so that the overall longitudinal bending stiffness of the board is of the order of twice that of a monolithic ski. When the ski is on the edge, only one beam bends, and its high stiffness is therefore necessary for the proper behavior of the board.

The lateral displacements can be variable according to the structures used.

As already mentioned, in practice, the characteristic recess is made at level of the front and / or rear ends of the board, and corresponds to a structural recess, meaning that at the level of this recess, the board has a very weak structure which is different from that of the rest of the ski, and especially in its lateral portions formed by the beams (2, 3).

Thus, as illustrated in FIG. 6, this recess can be completely free matter. It can, as illustrated in figure 7, be filled with an elastic material (31), such as a rubber foam, for example with closed cells.

In a variant illustrated in FIG. 8, this recess can receive the sole (32) of the board which extends from one side beam (2) to another (3). The material used to make the sole is relatively flexible, since it is usually polyethylene.

This matter only very slightly opposes the bringing together of one of the beams towards the median longitudinal plane (4) of the board.

It appears from the above that the ski according to the invention has a completely innovative structure in that it allows lateral bending under transverse stress without any comparison with existing skis.

This allows most of the length of the edge to come hang the snow, and therefore to facilitate the steering of the turn, whatever the radius of curvature that the skier wants to give it, as well as the inclination of the ski compared to the snow.

Claims (6)

Alpine ski (1), having a rib line (9) whose radius is less than 24 meters, the front (10) and / or rear (18) ends of which have a recess (11, 15) opening longitudinally at said end, characterized in that the ratio: VS BC = Y BC F BC · The 3 BC is greater than 0.3.10 ^-9 , in which L _av , and Y _av , expressed in millimeters, and F _av expressed in Newtons, are determined during the measurement in lateral flexion of the front part of the ski, measurement during which: the ski is placed on the side with its vertical gliding sole; the ski is kept locked at a front fixed point (20) located at a distance of 3/10 of the total length L _n of the ski, from the front end of the ski; a force F _av is exerted vertically on the edge of the ski, at an application point (21) located at a distance of 120 millimeters from the front end of the ski, said application point (21) therefore being located at a distance L _av = 0.3 x L _n - 120, measured in millimeters, from the front fixed point (20); the point of application undergoes a vertical displacement Y _av . Alpine ski (1), having a rib line (9) whose radius is less than 24 meters, the front (10) and / or rear (18) ends of which have a recess (11, 15) opening longitudinally at said end, characterized in that the ratio: VS ar = Y ar F ar · The 3 ar is greater than 0.3.10 ^-9 , in which L _ar , and Y _ar , expressed in millimeters, and F _ar expressed in Newtons are determined during the measurement in lateral flexion of the rear part of the ski, measurement during which: the ski is arranged on the side with its vertical gliding sole; the ski is kept blocked at a rear fixed point (24) located 3/10 of the total length L _n of the ski, from the rear end of the ski (8); a force F _ar is exerted vertically on the edge of the ski, at a point of application (25) located at a distance of 50 millimeters from the rear end of the ski (8), said point of application (25 ) being located at a distance L _ar = 0.3 x L _n - 50, measured in millimeters, from the rear fixed point (24); the application point (25) undergoes a vertical displacement Y _ar . Alpine ski according to one of claims 1 or 2, characterized in that it is formed by two longitudinal beams (2, 3) side by side, and associated at the level of the skate area. Alpine ski according to claim 3, characterized in that the beams (2, 3) are associated by a mounting platform for the binding (5). Alpine ski according to one of claims 1 or 2, characterized in that the recess (11,15) receives an elastic filling material. Alpine ski according to one of claims 1 or 2, characterized in that the ratio of the displacement in lateral flexion (Y _av , Y _ar ), divided by the total length L _n of the ski, is greater than 0.0015 when the force F exercised is 100 Newtons.

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