EP0806228B1 - Ski - Google Patents

Abstract

The ski consists of a body (2) with a supporting surface defined by front and rear contact lines (A,D') and a central zone (ZRC) of more or less constant thickness (E) and a length which is more than 40 per cent of the length (Lp) of the supporting surface. It has two zones (ZA and ZED) of variable thickness, located before and after central zone. The length of the central zone is between 600 and 900 mm, and its thickness is between 22 and 35 mm, or between 15 and 30 mm. The central zone of the ski can be made from one piece of material or in two layers, with the forward and rear sections joined to it by strips of a visco-elastic material.

Description

Technical area

The invention relates to the field of alpine skiing and cross-country skiing. She aims more particularly an improved geometry in which the variation thickness of the ski over its length gives very good sliding properties important.

Previous techniques

In general, a ski can be compared to a beam or a board slightly curved longitudinally to form the camber of the ski, with a part front raised to form the tip and a rear part also slightly raised to form the heel. The ski being laid flat on the snow, and under the effect of the skier's load, the bottom surface or sole remains in contact with the snow from the front contact line to the rear contact line. The distance between Front and rear contact lines determine the "bearing length" of the ski.

The geometry of this beam is precisely determined to give the ski the desired behavior, particularly in bending and torsion. So, generally speaking, the beam or the board has a certain flexibility which allows it to fit the shape of the terrain. The flexibility characteristics largely result from the variation in thickness of the board between the front and rear contact lines. In all skis known to date, the thickness of the ski increases continuously from the line front contact to the skate area in which it is maximum. This thickness then decreases continuously up to the rear contact line. Such a geometry is for example described in patent FR 2 700 476 in the case of a ski background.

This thickness distribution is generally combined with a variation of width of the ski according to its length, to give it a behavior specific.

This is how an alpine ski will be determined to achieve large curves or tight turns, to absorb fields of bumps or to evolve on smooth slopes, or to slide off piste on virgin snow. For a ski of bottom, it will either be designed to slide flat for "classic" practice, or provided to hang on the ridge for the "no skater".

Generally, the pressure exerted on the snow for a ski is maximum at the level of the skate, near the skier's foot, then decreases gradually until it disappears near the ends.

The shape of this pressure distribution curve is mainly related to the variation in thickness along the ski. The overpressure area of the shoe has a negative influence on the sliding characteristics of the board.

In other words, there is a certain incompatibility between the characteristics of flexibility necessary for the registration of the ski in the turn with optimization of the sliding qualities of the sole.

The problem which the invention therefore proposes to solve is to increase notoriously the sliding characteristics of a ski without modifying its dynamic behavior.

Statement of the invention

The invention therefore relates to a ski intended for the practice of alpine skiing or cross-country skiing, formed of a body and the sole of which has a bearing surface of length Lp delimited at the front and at the rear by the lines of contact respectively before A 'and rear D', and whose thickness is E _A at the level of the front contact line A 'and E _D at the level of the rear contact line D'.

• la surface portante se décompose en trois zones contiguës à savoir :
  • une zone centrale Z_BC d'épaisseur E sensiblement constante et dont la longueur L_BC est supérieure à cinquante pourcent (50%) de la longueur Lp de la surface portante;
  • deux zones avant Z_AB et arrière Z_CD d'épaisseur variable, localisées respectivement en avant et en arrière de la zone centrale Z_BC, et de longueurs L_AB et L_CD,
• en ce que le quotient E - E_A / L_AB de la différence d'épaisseur (E-E_A) du ski entre les points extrêmes (A,B) de la zone avant Z_AB, divisée par la longueur (L_AB) de la même zone est compris entre zéro virgule zéro un (0,01) et zéro virgule un (0,1);
• et en ce que le quotient E - E_D / L_CD de la différence d'épaisseur (E-E_D) du ski entre les points extrêmes (C,D) de la zone arrière, divisée par la longueur (L_CD) de la même zone est compris entre zéro virgule zéro un (0,01) et zéro virgule un (0,1).

This ski is characterized in that:

• the bearing surface is divided into three contiguous areas, namely:
  • a central zone Z _BC of thickness E substantially constant and whose length L _BC is greater than fifty percent (50%) of the length Lp of the bearing surface;
  • two zones before Z _AB and rear Z _CD of variable thickness, located respectively in front and behind the central zone Z _BC , and of lengths L _AB and L _CD ,
• in that the quotient E - E _A / L _AB of the difference in thickness (EE _A ) of the ski between the extreme points (A, B) of the front zone Z _AB , divided by the length (L _AB ) of the same area is between zero point zero one (0.01) and zero point one (0.1);
• and in that the quotient E - E _D / L _CD of the difference in thickness (EE _D ) of the ski between the extreme points (C, D) of the rear zone, divided by the length (L _CD ) of the same zone is between zero point zero one (0.01) and zero point one (0.1).

In other words, the invention consists in giving the ski a constant thickness in its central part, to ensure a uniform distribution of the pressure exerted on snow.

Concomitantly, to keep the necessary flexibility qualities when skiing for good dynamic behavior and registration in turns, zones located in front and behind the characteristic intermediate zone, are decreasing in thickness to the contact lines.

In other words, unlike all achievements in accordance with Art Anterior in which the thickness of the ski is continuously variable, a ski according to the invention has in its central area an upper face parallel to the sole.

Of course, the invention is not limited to skiing in which the thickness of the intermediate zone is strictly constant, but also covers achievements in which this thickness is substantially constant. By "substantially" constant we mean that the maximum difference in thickness on two points of this intermediate zone is at most equal to five percent (5%) of the total thickness.

We observed that we obtained good results in terms of sliding in the case where the length of constant thickness is between six hundred milllimeters (600 mm) and 900 millimeters (900 mm).

As already said, the invention relates to narrow skis used for cross-country skiing cross-country or for alpine skiing, on which the user's foot is positioned according to the longitudinal axis.

So in the case of cross-country skiing, we observed that we obtained a good improvement of sliding behavior when the thickness E of the area ZBC intermediate is between twenty two millimeters (22 mm) and thirty five millimeters (35 mm).

Similarly, in the case of alpine skiing, similar results are observed when the thickness E of the intermediate zone Z _BC is between fifteen millimeters (15 mm) and thirty millimeters (30 mm).

In this way, each ski of a pair being stressed independently at during a turn for alpine skiing or a boost for cross-country skiing, the pressure exerted by the sole of the shoe is uniformly transmitted over the entire carrying length of the ski. The constant thickness zone by its stiffness somehow plays a pressure distributing role, which improves the sliding ability.

As already mentioned, to maintain good charge progressivity, it it is important that the thickness of the ski decreases from the characteristic intermediate zone up to the front and rear contact lines.

Thus, on a cross-country ski, good dynamic behavior was observed when the quotient of the difference in thickness (EE _A ; EE _D ) of the ski between the extreme points (A, B; C, D) of each front zone Z _AB and back Z _CD , divided by the length (L _AB ; L _CD ) of the same area is between zero point zero three (0.03) and zero point zero nine (0.09).
In other words, 0.03 ≤ E - E _A / L _AB ≤0.09 and 0.03 ≤ E - E _D / L _CD ≤0.09

Similarly, good dynamic behavior of an alpine ski was observed when the quotient of the difference in thickness (EE _A ; EE _D ) of the ski between the extreme points (A, B; C, D) of each zone front Z _AB and rear Z _CD , divided by the length (L _AB ; L _CD ) of the same area is between zero point zero one (0.01) and zero point zero three (0.03). In other words, 0.01 ≤ E - E _A / L _AB ≤0.03 and 0.01 ≤ E - E _D / L _CD ≤ 0.03

Concerning the creation of the characteristic intermediate zone, several designs respect the principle of the invention.

Thus, in a first embodiment, the intermediate zone Z _BC is constituted by a monobloc part of the beam.

In a second embodiment, the intermediate zone Z _BC is constituted by the superposition of a part of the beam and of an upper element surmounting it.

In other words, the upper face of the ski receives in the intermediate zone features a rigid plate which ensures uniform transmission over its entire length of the weight and impulses generated by the skier, so that the distribution of the pressure exerted on the snow is as uniform as possible on the entire length of the characteristic intermediate zone.

In a first embodiment, the entire length of the element upper is glued on the beam.

In a sophisticated variant, the central part of the element upper is glued on the beam and the front and rear end parts of the reinforcing element are connected to the beam by strips of viscoelastic material. This reduces stress at the ends of the element and benefit from shear damping phenomena viscoelastic bands.

Concerning the geometry of the extreme zones of the upper element, several variants can be considered.

Thus, the front and rear end portions of this upper element can have vertical sections, corresponding to a thickness step. These parts extremals may also have inclined sides in the direction of the lines contact respectively front and rear, so as to ensure a variation of continuous thickness and without breakage.

The upper element can take different forms which prove to be interesting, either to manufacture or under the conditions of use.

Thus, in a first variant, the extreme front and rear parts of the upper element has inclined sides in the direction of the contact lines front A 'and rear D' respectively.

In other words, the upper element is presented in top view under a general rectangular shape.

In a second form variant, the front and rear end portions of the upper element conforms to a V shape, the point of which is directed towards the exterior of the top element.

In a variant intended to distinguish the behavior of the left skis and straight, the front and rear end parts of the upper element form in view from above, two non-parallel lines.

According to two construction variants, the beam and the upper element can either be of constant thickness, or be of complementary shapes of so that the thickness of the assembly is of constant thickness. In this last case In figure, the upper beam and element can be convex or concave.

Brief description of the drawings

The manner of carrying out the invention, as well as the advantages which flow therefrom will emerge clearly from the description of the embodiments which follow in support of attached figures in which:

Figure 1 is a side view of a ski according to the invention, in which the proportions have been exaggeratedly modified to allow good understanding of the dimensional criteria characteristic of the invention.

Figure 2 is a side view of a ski according to an alternative embodiment.

Figure 3 is a side view of a detail of the zone linking zone intermediates and before characteristics of the invention.

FIG. 4 is an alternative embodiment of FIG. 3.

Figures 5 to 7 are top views of skis having elements superior characteristics according to three variants of form.

FIG. 8 is a detail side view of the intermediate zone of a ski equipped with an upper element connected to the upper face of the ski partly by strips of viscoelastic material.

Ways to realize the invention

As already said, the invention relates to a ski, cross-country or downhill, which has a characteristic thickness variation along its length.

In known manner, a ski (1) mainly consists of a beam (2) of which the underside (3) forms the sole.

Only the part of the sole (3) between the front contact line (A ') and the rear contact line (D ') is intended to come into contact with the snow. The front part of the front contact line (A ') is raised upwards constitutes the spatula (4) while the rear part than the contact line rear (D ') is also raised, but to a lesser degree and constitutes the heel (5) skiing (1).

As is known, the thickness of the ski at the contact lines is less than the thickness measured in the bearing surface.

In FIG. 1, the thicknesses at the front (A ') and rear (D') contact lines are denoted E _A and E _{D respectively} .

According to an essential characteristic of the invention, the bearing surface, of length Lp, breaks down into three contiguous zones, namely: a central zone Z _BC surrounded by two zones respectively before Z _AB and Z _CD .

According to the invention, the central zone Z _BC extends over at least fifty percent (50%) of the length Lp of the bearing zone, and has a substantially constant thickness E.

Thus, in this central zone Z _BC , the upper face (6) of the ski and the sole (3) are substantially parallel.

As already said, by "substantially" constant, it should be understood that the difference maximum between the thicknesses measured at two points in this central zone ZBC is at most equal to five percent (5%) and preferably less than one percent (1%) of the total thickness E, while this difference is greater 25% and 10% respectively on a cross-country ski and an alpine ski in accordance with Prior Art.

According to another essential and dissociable characteristic of the invention, the variation in thickness on the zones before Z _AB and Z _CD , also meets precise criteria.

Thus, concerning the front zone, the quotient of the difference in thickness by the length is between 0.01 and 0.1, that is to say: 0.01 ≤ E - E _A / L _AB ≤ 0.1

Geometrically, this means that the ski being laid with its sole (3) flat on a horizontal plane, the slope between points A and B is between one for one hundred (1%) and ten percent (10%).

These dimensional parameters can be transposed to the rear zone Z _CD .

By way of example, it is considered that on a ski (1) of size 183 centimeters, the length Lp of the bearing zone being 158 centimeters, the intermediate zone Z _CD may have a length greater than 630 mm and more favorably 800 millimeters.

Furthermore, the thickness E of this same area must be between 15 and 35 millimeters, while the thickness E _A , E _D at the front and rear contact lines can vary at the same time between 4 and 12 millimeters .

According to another important characteristic of the invention, the area intermediate of constant thickness can be constituted either by a portion itself of the beam (2), or be formed of the association of the beam and an element upper (10) disposed on the upper face (6) of the ski.

In the case where the intermediate zone Z _BC is in one piece, it may or may not be seen there as a break in curvature at the points B and C constituting the limits of the intermediate zone, or else ensuring a smooth transition easier to manufacture.

As seen in Figures 3 and 4, the upper element may have ends (11, 12) of various geometries. So we can consider giving this end (11) a form of vertical pan (13) or else a form bevelled (14) ensuring a gradual thickness variation over a short range of transition.

Thus, we see in Figures 5 to 7, that the upper element (10) can marry various advantageous forms.

Thus, in a first variant, the upper element (10) has a substantially rectangular in shape, and the end portions (11, 12) terminate by straight segments (16, 17), mutually parallel and perpendicular to the median longitudinal plane of the ski.

In another variant, illustrated in FIG. 6, the extreme parts (11, 12) of the upper element (10) follow chevron shapes (18, 19) oriented by the ends of the ski. This allows the effect of pressure distributor of the upper element (10).

In a variant illustrated in FIG. 7, the ends (11, 12) of the element upper (10) follows the shapes of straight segments (20, 21) which, the converging extensions, on one side of the ski, substantially at the level of the length median of the upper element (10). This creates an asymmetry between the skis left and right.

As seen in Figure 8, the upper element (10) can be connected to the upper face (6) of the ski by gluing or other equivalent means, as illustrated only in its middle part.

In this case, the front and rear parts of the reinforcing element (10) are connected to the upper face (6) of the ski by strips of viscoelastic materials (25, 26), which allows a uniform distribution of pressure while ensuring a damping effect by shearing of the viscoelastic material.

It follows from the above that a cross-country or downhill ski conforming to the invention has, thanks to its variation in thickness over its length, qualities much better glide than previously existing skis.

By surprising effect, the dynamic behavior and in particular the registration in curve, is not modified.

Claims (17)

1. Ski (1) intended for downhill skiing or cross-country skiing, formed of a body (2) and the sole (3) of which has a bearing surface of length Lp delimited at the front and at the rear by lines of contact, namely a front line of contact A' and a rear line of contact D', and the thickness of which is E_A at the front line of contact A' and E_D at the rear line of contact D', characterized

   in that the bearing surface can be broken down into three contiguous zones, namely:

   a central zone Z_BC of essentially constant thickness E and the length L_BC of which is greater than fifty per cent (50%) of the length Lp of the bearing surface;

   two, front Z_AB and rear Z_CD, zones of variable thickness, located one in front and the other behind the central zone Z_BC, and with lengths L_AB and L_CD,

   in that the quotient E - E_A / L_AB of the difference in thickness (E-E_A) of the ski between the extreme points (A, B) of the front zone, divided by the length (L_AB) of the same zone is between zero point zero one (0.01) and zero point one (0.1)

   and in that the quotient E - E_D / L_CD of the difference in thickness (E-E_D) of the ski between the extreme points (C, D) of the rear zone, divided by the length (L_CD) of the same zone is between zero point zero one (0.01) and zero point one (0.1).
2. Ski according to Claim 1, characterized in that the length L_BC of the intermediate zone Z_BC is between six hundred millimetres (600 mm) and 900 millimetres (900 mm).
3. Ski according to Claim 1, characterized in that it is intended for cross-country skiing, and in that the thickness E of the intermediate zone Z_BC is between twenty-two millimetres (22 mm) and thirty-five millimetres (35 mm).
4. Ski according to Claim 1, characterized in that it is intended for downhill skiing, and in that the thickness E of the intermediate zone Z_BC is between fifteen millimetres (15 mm) and thirty millimetres (30 mm).
5. Ski according to Claim 1, characterized in that it is intended for cross-country skiing, and in that the quotient of the difference in thickness (E-E_A; E-E_D) of the ski between the extreme points (A, B; C, D) of each front zone Z_AB and rear zone Z_CD, divided by the length (L_AB; L_CD) of the same zone is between zero point zero three (0.03) and zero point zero nine (0.09).
6. Ski according to Claim 1, characterized in that it is intended for downhill skiing, and in that the quotient of the difference in thickness (E-E_A; E-E_D) of the ski between the extreme points (A, B; C, D) of each front zone Z_AB and rear zone Z_CD, divided by the length (L_AB; L_CD) of the same zone is between zero point zero one (0.01) and zero point zero three (0.03).
7. Ski according to one of Claims 1 to 6, characterized in that the intermediate zone Z_BC consists of a monoblock part of the beam (3).
8. Ski according to one of Claims 1 to. 6, characterized in that the intermediate zone Z_BC consists of the superposition of part of the beam (3) and of an upper element (10) surmounting it.
9. Ski according to Claim 8, characterized in that the entire length of the upper element (10) is bonded onto the beam (3).
10. Ski according to Claim 8, characterized in that the central part of the upper element (10) is bonded onto the beam (3) and in that the front and rear extreme parts (11, 12) of the upper element (10) are connected to the beam (3) by strips (25, 26) made of visco-elastic material.
11. Ski according to Claim 8, characterized in that the front and rear extreme parts (11, 12) of the upper element (10) have vertical facets (13).
12. Ski according to Claim 8, characterized in that the front and rear extreme parts (11, 12) of the upper element (10) have facets (14) which are inclined towards the front A' and rear D' lines of contact, respectively.
13. Ski according to Claim 8, characterized in that the front and rear extreme parts (11, 12) of the upper element (10) are formed of segments (16, 17) which are straight, parallel and perpendicular to the longitudinal mid-plane of the ski.
14. Ski according to Claim 8, characterized in that the front and rear extreme parts (11, 12) of the upper element (10) have the shape of a V, the point (18, 19) of which points towards the outside of the upper element (10).
15. Ski according to Claim 8, characterized in that the front and rear extreme parts of the upper element, when viewed from above, form two non-parallel lines.
16. Ski according, to Claim 8, characterized in that the beam and the upper element are both of constant thickness.
17. Ski according to Claim 8, characterized in that the beam and the upper element are of complementing shape so that the thickness of the entity is constant.

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