EP0370197A1 - Ski provided with a lateral inertia mass - Google Patents

Abstract

The ski according to the invention has a lightweight structure and is equipped with at least one element (81, 82) of a density higher than the average structural density of the ski and forming an additional inertia mass. According to the invention, the said additional inertia mass is distributed eccentrically on either side of the longitudinal mid-axis (II-II) of the ski and constitutes an assembly equivalent to two flyweights (81, 82) offset on either side of the mid-axis of the ski. <IMAGE>

Description

The present invention relates to skis in which one or more additional masses of inertia make it possible to modify and adjust the moment of inertia of the ski both around a vertical axis, around a horizontal axis perpendicular to the direction longitudinal of the ski, and around the longitudinal axis of the ski.

The moment of inertia around the vertical axis, or axis of rotation of the ski, influences the behavior of the ski in rotation, by determining the resistance that the ski opposes to a variation in the direction of movement. A ski with a low moment of inertia, for example a short ski or a light ski at its ends, is easier to turn than a ski with a high moment of inertia. An easy to turn ski is particularly suitable for special snow conditions such as deep snow, spring snow, and for special terrain conditions such as bumpy slopes. A ski with a high moment of inertia, for example an elongated ski or a ski having relatively large masses at its ends, is particularly stable in direction during a rapid descent, because the forces exerted laterally on the ski by the Track unevenness is better absorbed due to the higher moment of inertia.

The moment of inertia of the ski around its central horizontal axis perpendicular to the longitudinal direction of the ski influences the vibratory behavior of the ski. We know that vibrations can be harmful, and lead to a loss of grip on the ground at the edges of the ski, and, consequently, to directional instability.

Furthermore, modern ski construction techniques lead to the production of increasingly light ski structures, comprising for example a central core of light cellular material, surrounded by a structure of mechanical strength in a box. The lightness of such a structure leads to a significant reduction in the moment of inertia and to the introduction of the faults mentioned above. We know that such defects can be corrected by adapting additional inertia masses.

Thus, from German patent No. 2,052,332, a ski is known in which, in order to modify its moment of inertia, masses centered on the longitudinal axis of the ski can be moved in the direction of its length and immobilized on or inside its posterior part or earlier. By modifying the distance of the masses at the two ends of a ski, one can vary its moment of inertia both around the vertical axis and around the central horizontal axis perpendicular to its longitudinal direction. The practical implementation of this system is however very difficult and costly. The arrangement of the masses outside the ski cannot be used in practice, by the fact that snow can accumulate in the adjustment members and prevent their operation. The arrangement of the masses inside the ski annoyingly weakens the section of the ski, and requires the construction of entirely new skis with hollow section and mechanical displacement. It also appears that such an adjustable structure does not make it possible to position the additional inertia masses in the zones which provide a satisfactory result, since these zones have a thickness too small to accommodate the mechanics of displacement of the masses of inertia. The satisfactory location of these areas is the subject of the present invention, and will be explained in detail in the description which follows.

French patent FR-A-2 382 245 teaches to have additional masses of inertia in the longitudinal axis of the ski on the upper surface of the ski, at the two ends of the ski. This document does not include any teaching on the positioning of inertia masses in the particular zones which provide an appropriate effect as will be described below.

During its evolution, a ski is not only subjected to bending and pivoting forces, but also to torsional forces and excitations. The present invention results from the observation that it is possible to modify appreciably and advantageously the natural modes of torsional vibration and the damping of the ski by placing additional masses of inertia no longer in the longitudinal axis of the ski, but distributed by on either side near the edges of the ski. This results in a significant improvement in the handling of the ski in the curves, and in the length of attachment of the ski to the snow. It is understood that the provision of additional masses of inertia in the vicinity of the edges of the ski increases the moment of inertia of the ski around its longitudinal axis.

With such a ski according to the invention, the precision and regularity of driving a turn is significantly improved, by reducing sensitivity of the ski to the terrain of the piste; directional stability is significantly improved to make it similar to that of heavy skis, without however increasing the total weight of the ski and keeping it at a value substantially lower than that of heavy skis. The ski can be easily oriented at low speed of movement or rotation, while its relatively high moment of inertia around its longitudinal axis absorbs the rapid stresses imparted by the reliefs of the track during turns. This results in less physical and psychological fatigue for the skier.

To achieve these and other objects, the ski according to the present invention comprises a light structure, with a cell nucleus, and is provided with at least one element of density greater than the average density of structure of the ski body and constituting a additional mass of inertia arranged in a suitable longitudinal position along the ski body; according to the invention, said additional mass of inertia is distributed off-center on either side of the vertical longitudinal median plane of the ski, so as to constitute an assembly equivalent to two weights offset respectively on either side of the plane vertical longitudinal median of the ski, said assembly having an appropriate moment of inertia with respect to the longitudinal axis of the ski.

According to an advantageous embodiment, the additional mass of inertia is a plate of non-uniform thickness, the thickness being small in the vicinity of the longitudinal axis of the ski and being greater in the vicinity of the edges of the ski.

According to another possibility, the additional mass of inertia is a plate of non-uniform length, the plate length being shorter in the vicinity of the longitudinal axis of the ski and being greater in the vicinity of the edges of the ski. This characteristic of non-uniform length can moreover be combined with the characteristic of non-uniform thickness mentioned above.

According to one embodiment, the additional mass of inertia comprises two separate lateral half-masses disposed respectively on either side of the longitudinal axis of the ski in the vicinity of the edges of the ski.

In practice, the additional masses of inertia can be placed on the upper surface of the ski.

Preferably, the additional inertia masses are incorporated porées in the internal structure of the ski. In particular, the lateral portions of additional inertia masses can be advantageously incorporated into the lateral portions of the ski on either side of the central cellular core.

In the embodiments in which the ski comprises inclined lateral edges, the inclination being such that the width of the ski is greater in the vicinity of its base than in the vicinity of its upper face, the lateral portions of inertia masses additional are shaped to follow the inclination of the edges, so that the center of gravity of the ski is thus lowered.

• - la figure 1 est une vue schématique de côté d'un ski selon la présente invention, posé à vide sur un plan ;
• - la figure 2 illustre la répartition des pressions de contact sous la face inférieure du ski ;
• - la figure 3 représente, en vue de dessus, la position de la masse d'inertie additionnelle avant selon un premier mode de réalisation de l'invention ;
• - la figure 4 est une vue de côté du ski de la figure 3 ;
• - la figure 5 est une vue en coupe transversale selon le plan I - I de la figure 3 ;
• - la figure 6 représente, en vue de dessus, un second mode de réalisation de la masse d'inertie additionnelle avant ;
• - la figure 7 représente, en vue de dessus, un troisième mode de réalisation de la masse d'inertie additionnelle avant, comportant deux demi-masses latérales ;
• - la figure 8 est une vue en coupe transversale selon le plan I - I de la figure 7 ;
• - la figure 9 illustre un autre mode de réalisation de la masse d'inertie additionnelle avant selon l'invention ; et
• - la figure 10 illustre un mode de réalisation de la masse additionnelle arrière selon l'invention.

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

• - Figure 1 is a schematic side view of a ski according to the present invention, placed empty on a plane;
• - Figure 2 illustrates the distribution of contact pressures under the underside of the ski;
• - Figure 3 shows, in top view, the position of the front additional inertia mass according to a first embodiment of the invention;
• - Figure 4 is a side view of the ski of Figure 3;
• - Figure 5 is a cross-sectional view along the plane I - I of Figure 3;
• - Figure 6 shows, in top view, a second embodiment of the additional front inertia mass;
• - Figure 7 shows, in top view, a third embodiment of the additional front inertia mass, comprising two lateral half-masses;
• - Figure 8 is a cross-sectional view along the plane I - I of Figure 7;
• - Figure 9 illustrates another embodiment of the additional front inertia mass according to the invention; and
• - Figure 10 illustrates an embodiment of the rear additional mass according to the invention.

As shown in Figures 1 and 2, the ski according to the present invention comprises, in a traditional manner, a ski body 1 the central part of which is curved, curved in an upward arc and the two ends of which are raised upwards, the front end forming a spatula 2, the rear end 3 also being raised upwards.

When the ski rests, empty, on a plane 4, the bending of the central part of the body 1 causes the ski to rest on the plane 4 along two transverse lines, a transverse front contact line 5, a transverse rear contact line 6. When in use, the ski is intended to rest on the ground according to its lower contact surface 7, which surface is limited by the two lines 5 and 6.

An additional front inertia mass 8 is placed in the vicinity of the front transverse contact line 5. An additional rear inertia mass 9 is placed in the vicinity of the rear transverse contact line 6.

According to a first possibility, the additional masses of inertia 8 and 9 are fixed on the upper surface 10 of the ski.

According to another embodiment, the additional inertia masses 8 and 9 are fixed and incorporated in the body of the ski, being non-visible or only partially visible on the upper surface 10 of the ski.

There is shown, in Figure 2, a ski according to the present invention provided with its two additional masses of inertia 8 and 9, placed on a flat surface 4, and subjected to a load such as the weight of a user. Under the effect of the load, the lower contact surface 7 of the ski is entirely in contact with the plane 4. However, by the effect of the bending of the ski body, the contact pressure between the lower ski surface 7 and the plane 4 varies as a function of the longitudinal position considered along the ski. This pressure has a maximum 11 under the central zone occupied by the bindings and receiving the weight of the skier. This pressure then has a minimum on either side of the maximum 11, namely a minimum 12 in the front third of the ski and a minimum 13 in the rear third. The pressure has a relative maximum 14 in the vicinity of the front transverse contact line 5 of the ski and a second relative maximum 15 in the vicinity of the rear transverse contact line 6 of the ski. It can therefore be seen that, when the additional inertia masses 8 and 9 are positioned in the vicinity of the front contact lines 5 and rear 6 of the ski, their position corresponds to a relative maximum of contact pressure below the surface of the ski.

There is shown in Figures 3 to 5, a first embodiment of an additional mass of inertia before skiing. According to this first embodiment, the additional mass of inertia 8 before is in one piece, and is distributed in a non-uniform manner on either side of the median longitudinal axis II - II of the ski. It may for example be a plate with a density greater than the average density of the ski body 1. The additional mass of inertia 8 extends to the vicinity of the edges 16 and 17 of the ski. The additional mass of inertia 8 comprises a central zone 85 connecting a first lateral zone 86 arranged in the vicinity of the edge 16 of the ski and a second lateral zone 87 arranged in the vicinity of the second edge 17 of the ski. The central zone 85 has a relatively small thickness E in comparison with the thickness of the lateral zones 86 and 87. In the embodiment shown in FIG. 5, the central zone 85 is arranged above the central core 19 with a cellular structure of the ski. According to another variant, not shown in the figures, the central zone 85 of the additional mass of inertia can be arranged below the central core 19.

In the embodiments which have been shown in the figures, the ski comprises lateral edges 16 and 17 inclined. The lateral portions 86 and 87 of additional inertia masses are advantageously shaped to follow the inclination of the edges. In this case, it can advantageously have a greater width in the vicinity of the lower sliding surface 7 of the ski than in the vicinity of the upper surface 10 of the ski. In this way, the presence of the additional inertia masses lowers the center of gravity of the ski, that is to say, brings it closer to the lower sliding surface 7. In the embodiment shown in FIG. 5, the lateral zones 86 and 87 of the additional inertia mass 8 have a triangular section and occupy the entire available section between the side edges 16 and 17 and the side faces of the central core 19.

In the embodiment shown in FIG. 6, the additional front mass of inertia 8 is a plate comprising a central cutout 18 in V, so that the mass 8 is distributed in a privileged manner in the vicinity of the edges 16 and 17 of the ski . In other words, the length of the plate forming the additional mass of inertia before 8 is not uniform, this length being shorter in the vicinity of the longitudinal axis II - II of the ski and being greater in the vicinity of the edges 16 and 17 of the ski. This embodiment can be combined with the previous characteristic according to which the thickness of the plate forming the additional front mass of inertia 8 of the ski is smaller in the vicinity of the longitudinal axis II - II of the ski and greater in the vicinity side edges 16 and 17 of the ski.

In Figures 7 and 8, there is shown an embodiment in which the additional mass of inertia before 8 of the ski consists of two half-masses 81 and 82, the first half-mass 81 being arranged along the edge 16 ski, the second half-mass 82 being disposed along the ski edge 17. The ski according to the invention advantageously has a cellular structure, with a central core 19 of constant width. The core 19 is thus bordered, over part of its length, by the half-masses 81 and 82, as shown in FIG. 8.

In the embodiments in which the edges 16 and 17 of the ski are inclined, as shown in FIG. 8, the half-masses 81 and 82 are advantageously shaped to follow the inclined shape of the edges.

When this proves useful, it is possible to associate a third additional mass of inertia 20, centered on the longitudinal axis II - II of the ski, with two lateral half-masses 81 and 82, as shown in FIG. 7 .

Alternatively, several lateral inertia masses can be distributed in the vicinity of the front contact line 5. For example, in FIG. 9, the two lateral half-masses 81 and 82 are shown, similar to the half-masses of the modes of previous embodiments, but associated with two additional lateral auxiliary masses 83 and 84 arranged slightly behind the additional masses 81 and 82.

FIG. 10 shows an embodiment in which the rear additional inertia mass 9 consists of two lateral half inertia masses 91 and 92 disposed respectively in the vicinity of the edges 16 and 17 of the ski.

Preferably, the additional mass of inertia before 8 is distributed on either side of the vertical plane I - I passing through the transverse line of contact before 5 along a certain length, of the order of 15 to 25 centimeters. The distance L1 between the anterior end of the additional mass of inertia 8 and the vertical plane I - I passing through the front transverse contact line 5 is advantageously between 0 and 10 centimeters; similarly, the length L2 between the rear end of the additional mass of inertia 8 and the vertical plane I - I passing through the front transverse contact line 5 is advantageously between 0 and 15 centimeters.

For the types of ski corresponding to a preferred type of evolution, for example a slalom ski, a giant slalom ski, a downhill ski, or a multi-purpose ski, it is possible to approximately adapt the behavior of the ski by adjusting the value of the additional inertia masses 8 and 9. One will advantageously choose an additional inertia mass before 8 of value between 40 and 200 grams, and an additional rear inertia mass 9 of value between 0 and 100 grams. In general, the additional front mass of inertia 8 has a value greater than the rear additional mass of inertia 9, the difference between the two masses possibly being of the order of 50 grams.

It has been observed that, when the additional mass of inertia before 8 has a value exceeding 75 grams, it is necessary to compensate for the oversteering effect thus obtained by placing an additional mass of inertia 9 at the rear.

In practice, the additional masses may consist of lead plates or other heavy materials. They can be placed in housings provided for this purpose. The housing of the additional masses can be carried out by any conventional machining means such as milling, routing, either in the central part 19 forming the core, or in the lateral parts called edges. Similarly, the additional inertia masses can be partially housed in housings provided in the core 19 and partially housed in the side edges of the ski.

The nature of the additional inertia masses can be a composite material, combining the forming and adhesion qualities of a thermoplastic material with the density qualities of a metal such as lead, brass, tungsten.

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 (12)

1 - Ski with light structure, provided with at least one element (8) of density greater than the average density of structure of the body (1) of ski and constituting an additional mass of inertia (8) arranged in an appropriate longitudinal position along the ski body (1), characterized in that said additional mass of inertia (8) is distributed in an off-center fashion on either side of the median longitudinal vertical plane (II - II) of the ski, so as to constitute an assembly equivalent to two weights offset respectively on either side of the median longitudinal vertical plane (II - II) of the ski. 2 - Ski according to claim 1, characterized in that the additional mass of inertia (8) is a plate of non-uniform thickness, the thickness (E) being small in the central part (85) in the vicinity of the longitudinal axis (II - II) of the ski and being more important in the lateral parts (86, 87) in the vicinity of the lateral edges (16, 17) of the ski. 3 - Ski according to one of claims 1 or 2, characterized in that the additional mass of inertia (8) is a plate of non-uniform length, the length being shorter in the vicinity of the longitudinal axis (II - II ) of the ski and being more significant in the vicinity of the side edges (16, 17) of the ski. 4 - Ski according to claim 1, characterized in that the additional mass of inertia (8) comprises two lateral half-masses (81, 82) disposed respectively on either side of the longitudinal axis (II - II) of the ski in the vicinity of the side edges (16, 17) of the ski. 5- Ski according to any one of claims 1 to 4, characterized in that the additional inertia masses (8, 9) are fixed on the upper surface of the ski. 6 - Ski according to any one of claims 1 to 4, characterized in that the additional masses of inertia (8, 9) are incorporated in the internal structure of the ski. 7 - Ski according to claim 6, characterized in that the lateral parts (86, 87) of additional inertia masses (8) are incorporated in the lateral ski portions on either side of the central core (19). 8 - Ski according to claim 7, characterized in that it comprises inclined lateral edges (16, 17), and in that the lateral portions (86, 87) of additional inertia masses are shaped to follow the inclination of the edges. 9 - Ski according to claim 8, characterized in that the lateral portions (86, 87) of additional inertia masses have a greater width in the vicinity of the lower sliding surface (7) than in the vicinity of the upper surface (10) skiing. 10 - Ski according to claim 9, characterized in that the lateral portions (86, 87) of additional inertia masses have a triangular cross section. 11 - Ski according to any one of claims 1 to 10, characterized in that it comprises an additional mass of inertia (8) before disposed in the vicinity of the front transverse contact line (5) of the ski. 12 - Ski according to any one of claims 1 to 11, characterized in that it comprises an additional rear mass of inertia (9) disposed in the vicinity of the rear transverse contact line (6) of the ski.

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