ALPINSKI WITH IMPROVED SIDELINE

Description

Domaine technique :

[0001] The invention relates to the field of snow sports equipment, and in particular alpine skis.

[0002] It specifically targets an alpine ski with a particular sidecut, giving it specific properties in terms of behavior on snow, especially for advanced competitive practices. Techniques antérieures :

[0003] Generally, an alpine ski has different zones distributed along its length: a tip zone at the front, curved upwards to overcome obstacles; a tail zone at the rear of the ski, also slightly upturned; and a waist zone extending between the tip and tail. The waist zone provides the ski's glide via its underside, which is formed by a glide base bordered by edges, and on its upper side, it receives the mounting elements for the safety binding.

[0004] Generally, although not mandatory, skis exhibit symmetry about their median longitudinal plane, which extends from the front to the rear of the ski. The sidecut is defined as the line that represents the lateral contour of the ski, which may be more or less deep.

[0005] In a standardized way, a "rear contact line" and a "front contact line" are defined on the ski, which are the front and rear limits of the contact surface of the underside when the ski is applied to a flat surface, in particular by loading the ski at the waist to cancel its camber.

[0006] Simultaneously, a sidecut is defined between the two widest points of the ski, located at the front and rear. A trend has been observed towards alpine skis where the widest point is located beyond the front contact line, so that the ski widens somewhat in the tip section before reaching the front point. The same trend is observed for the rear section of the ski, with a line of greatest width at the rear, which can be located further back than the rear contact line, even within the tail area itself.

[0007] Numerous solutions have been proposed to generate specific behaviors when skiing, ensuring a greater or lesser degree of sidecutting.

[0008] Traditionally, skis are designed to have a sidecut in the waist area that fits into a circle, so that the radius of curvature of the sidecut is generally constant over the entire waist, with a well-localized center of curvature, causing the tracing of curves to be roughly centered on this point.

[0009] Other solutions have been proposed to ensure a progression or variation of the radius of curvature along the sidecut, such as the one illustrated in Applicant's document FR2985914. The sidecut of the ski described in this document varies so that it is oriented outwards in the central part of the waist and inwards in the front and rear areas of the waist, extending to the tip and tail, respectively. This geometry is intended to ensure a specific distribution of forces along the sidecut when the ski is tilted on its edge, in order to make ski control easier.

[0010] This configuration is therefore not necessarily compatible with a quest for performance, particularly in competitive skiing. Document EP 2082787 A1 discloses a ski according to the preamble of claim 1. Description de l'invention

[0011] To solve this problem, the invention proposes an alpine ski comprising a tip area at the front of the ski, a waist area, and a tail area at the rear of the ski, a median longitudinal plane extending from the front to the rear of the ski, and an underside formed by a glide base bordered by edges. Typically, this ski includes a binding mounting area, the position of which is determined by a "mounting point" (MP), as defined in ISO 6289 and ISO 5355. This mounting point is intended to be aligned longitudinally with a reference mark on the boot held by the binding, located at the level of a boot centerline (BC). In the following, the mounting point and the boot centerline are assumed to be at the same longitudinal level and are therefore considered to coincide on this plane.

[0012] The sidecut of this ski features: a front contact line (PA) defined as the contact line between the glide sole and a horizontal surface on which the sole is pressed when the skate is loaded, which is located furthest forward, a rear contact line (PB) defined as the contact line between the glide sole and said horizontal surface, which is located furthest back, a front line of greatest width (P1) located at or further forward than the front contact line (PA), a rear line of greatest width (P2) located at or further back than the rear contact line (PB), a minimum width zone (P3) located in the skate zone. said dimension line having a variable radius of curvature between the front contact line (P HAS ) and the rear contact line (P B ), the width of the ski, measured perpendicular to the median longitudinal plane, at the level of the front contact line (PA) is strictly less than the width of the ski measured at the level of the rear contact line (PB).

[0013] In other words, the width of the ski at the boundary between the waist and the tail is greater than the same width measured at the boundary between the waist and the tip. Put another way, the width of the gliding zone is greater behind the waist than in front of it.

[0014] According to the invention, the minimum width zone (P III) of the ski is located further forward than the middle line of the boot (MC).

[0015] According to the invention, the radius of curvature has a maximum value at a transverse line located strictly between the front contact line (PA) and the rear contact line (PB),

[0016] And the ratio between the maximum radius of curvature value and the radius of curvature value at the front contact line is greater than 2.5, preferably greater than 3.

[0017] In other words, the invention consists of giving the ski a particular geometry in which the radius of curvature is highly variable between the front contact line and the rear contact line, with a very marked maximum, i.e. a relatively low curvature in this area, compared to the curvature measured near the heel and the tip.

[0018] In other words, the ski according to the invention has a relatively straight sidecut in the area where the boot is located, whereas, on the contrary, as you approach the front and rear contact lines, i.e. the ends of the ski, you find a more pronounced curvature, ensuring the hollowing of the sidecut.

[0019] In practice, it has been observed that ski performance is significantly improved and advantageous in competition, while maintaining forgiving handling of uneven terrain, when the ratio between the maximum turning radius and the larger of the two turning radii at the front and rear contact lines exceeds 2.5. This ratio can be even higher, exceeding 3, or even 4 for advanced competition skis. In other words, a particularly advantageous geometry is one in which the difference between the very large turning radius at the center of the waist zone and the larger of the relatively small turning radii at the front or rear contact line is greatest.

[0020] In parallel, the Applicant observed that this geometry is particularly advantageous when the boot's centerline is slightly set back from the ski's narrowest point. In other words, the ski's narrowest point is located in front of the boot's centerline. The ski's performance is further improved when the area of ​​very low camber is positioned in front of the boot's centerline, notably for ease of initiating turns and entering curves.

[0021] Advantageously, in practice, the difference between the width at the front contact line (PA) and the width at the rear contact line (PB) is between 2 and 10 mm,

[0022] In preferred embodiments, the distance between the minimum width zone (PIII) and the shoe center line (MC) is greater than 2 mm, preferably 5 mm, and less than or equal to 100 mm.

[0023] According to another feature of the invention, the variation of the radius of curvature of the dimension line according to the longitudinal position of the measurement point is a function whose second derivative with respect to said longitudinal position is positive for a longitudinal position between the rear contact line and the front contact line.

[0024] In other words, the radius of curvature along the sidewall is measured in such a way that it increases progressively from the rear contact point towards the point of maximum curvature. Conversely, it decreases progressively from the maximum towards the front contact point. Put another way, the variation in the radius of curvature increases from the rear contact point towards the point of minimum curvature, and this same variation decreases from the maximum towards the vicinity of the front contact line.

[0025] Advantageously, in practice, the transverse line where the radius of curvature is maximum is located approximately at the narrowest point of the ski (P III). In other words, the narrowest point of the ski corresponds almost exactly, within 5 millimeters, to the point where the curvature is the least, and where the sidecut is closest to a straight profile. Brève description des figures

[0026] The invention will be well understood, and its advantages and various other features will become apparent, from the following description of some non-limiting embodiments, with reference to the accompanying schematic drawings, in which: [ Fig.1 ] There figure 1 and a schematic side view of a ski according to the invention, showing unloaded. Fig.2] FIG. 2 there figure 2 is a side view of the ski slope figure 1 , show loaded, with its underside pressed against a horizontal surface. Fig.3 ] There figure 3 is a schematic top view of the ski figures 1 et 2 showing the various dimensional parameters characteristic of the invention. Fig.4 ] There figure 4 is a diagram illustrating the variation in width measured along the ski of the figure 3 , as well as the variation in the radius of curvature.

[0027] Of course, the representations given in the figures are only schematic, and some proportions may differ from reality, in order to better explain the invention. Description des modes de réalisation

[0028] For clarity, we define a reference point Oxyz as well as plans xy, yx And xz defined from the vectors x, y And z non-collinear of the reference frame Oxyz. For simplicity, we will consider that the forward direction corresponds to the longitudinal direction of the ski along the Ox axis, oriented from the waist towards the tip.

[0029] In general, a ski has dimensional parameters that are defined according to the ISO 6289 standard.

[0030] Thus, as illustrated in the figure 1 skiing 1 features a spatula area at the front 2 and at the back a heel area 3 separated by the central zone 4, also called the skating zone. When ski 1 is placed on a horizontal plane 10, Without being loaded, the camber it exhibits at the level of the skid area causes it to come into contact with this horizontal plane at two specific points 5 ;6 forwards and backwards.

[0031] As illustrated in the figure 2 When this ski 1 is loaded, that is, when it bears the weight of a user, the camber of the waist area changes. 4 is thwarted, the gliding sole comes into contact with the horizontal plane 10 on a sliding area. This sliding area 12defined between two particular lines, namely the front contact line P A , marking the rear boundary of the spatula 2, and the rear contact line P B forming the front boundary of the heel area 3.

[0032] In addition, and as illustrated in the figure 3 Ski 1 has a width that varies from the tail 3 up to the spatula 2. This width, measured perpendicularly to the median longitudinal plane, along the axis Oy presents localized extremities. Thus, in the heel area 3, ski 1 has a maximum width at the point P II In the embodiment illustrated in the figures, it should be noted that this point P II is located behind the point P B corresponding to the rear contact line. On the other side of the ski, it has a maximum width at the point P I , at a level located further forward than the forward contact line P A .

[0033] The ski also has a minimum width in the waist zone, at the point P III .

[0034] In some cases, the Applicant observed that a particular behavior could be observed when the width of the ski at the point P B The width of the ski, at the level of the rear contact line, near the heel area, is greater than the width of the ski at the point P A of the ski, at the level of the front contact line, near the tip area. More precisely, this difference in width (L P B - L P A ) can be in the range of 2 to 10 millimeters, and leads to a behavior on snow that favors the pivoting of the ski and allows it to be more tolerant of imperfections in the terrain.

[0035] As illustrated in the figure 3 The ski has a zone where the safety binding is designed to be mounted, in order to accommodate the user's boot. This zone is marked by the region 20 dotted lines on the figure 3 , and essentially defined by the line M C corresponding to the middle of the shoe. This point M C allows, in particular, for the heel piece and the binding's toe piece to be positioned symmetrically, relative to this point M C , to take into account the user's shoe size, or the installation of a platform in which the toe piece and heel piece of the binding are adjustable in position.

[0036] The Applicant noted the advantage of a configuration in which the minimum width zone P III is located further forward than the midline of the shoes M C In particular, this gap can be greater than 2 mm, or even greater than 5 mm, and preferably between 5 and 15 mm. This parameter makes it easier for the ski to enter the turn at the beginning of the turn.

[0037] The skis conforming to the invention have a particular geometry, especially with regard to the radius of curvature. R C of the coastline. In practice, this radius of curvature can be measured from the variation in the width of the ski, measured along the longitudinal direction. Ox. Thus, from a profile measurement of the ski's width along the axis O X, it is possible by calculation to determine the curvature, and the radius of curvature (which is the inverse of the curvature) to draw a curve as illustrated in the figure 4 More precisely, the second derivative of the ski width measurement curve yields the curve representing the ski's curvature along the sidecut. Of course, other practical methods can be used to calculate this radius of curvature, particularly by using mechanical devices that are moved along the sidecut. By approximating the sidecut with a third-degree polynomial, for example, it is possible to differentiate this polynomial twice to obtain the curve representing the radius of curvature along the ski. Empirically, using the coordinates of three sliding points moving along the sidecut, it is also possible to calculate the radius of curvature.

[0038] According to the invention, the radius of curvature exhibits a specific variation such that it has a maximum value R MAX located nearby, or even confused with the point of smallest width PIII. The value of the maximum turning radius is particularly high, greater than 35 m, or even 50 m, preferably between 50 and 80 m. This maximum value allows in particular the adjustment of the degree of grip of the ski.

[0039] In addition, and as illustrated in the figure 3 The radius of curvature is significantly smaller as you move towards the tips of the ski. At the tips of the ski, at the points P A and P B, the radii of curvature are between 5 and 20 m, preferably between 10 and 20 m.

[0040] We observe on the figure 4 that the minimum values ​​of the radius of curvature at the front R MAX-AV and at the rear R MAX-AR are significantly lower than the maximum radius value R MAX, in a ratio of at least 2.5 or preferably greater than 3, or even 4.

[0041] In addition, the evolution of the radius of curvature is also specific for skis conforming to the invention, since, as can be seen in the figure 4 , the second derivative of the radius of curvature calculated along the axis O X is such that it is always positive, meaning that the closer one gets to the point where the radius of curvature is maximum, the more rapidly this radius of curvature increases.

[0042] The geometry of the skis according to the invention is particularly advantageous for its performance qualities on snow while remaining easy to handle. More specifically, these skis offer easy turn initiation and a distribution of pressure along the entire length of the ski, preventing excessive edge grip. Such skis have a narrower tip, making them easier to maneuver as they do not generate unwanted edge grip at the front.

Claims

1. Alpine ski (1) comprising a tip zone (2) located at the front of the ski, a waist zone (4), and a tail zone (3) located at the rear of the ski, a median longitudinal plane extending from the front end to the rear end of the ski, an underside formed by a gliding sole (7) bordered by edges, a zone for mounting a boot (20), the middle of which, in the longitudinal direction, is located at a mid-shoe line (MC), and having a sidecut with: - a front contact line (PA) defined as the line of contact between the gliding sole (7) and a horizontal surface (12) against which the sole is pressed when the waist (4) is loaded, which is located furthest forward, - a rear contact line (PB) defined as the line of contact between the gliding sole (7) and said horizontal surface, which is located furthest back, - a line of greater front width (PI) located at or further forward than the front contact line (PA), - a line of greater rear width (PII), located at or more rear than the rear contact line (PB), - a zone of minimum width (PIII) located in the waist zone, said sidecut having a variable radius of curvature between the front contact line (PA) and the rear contact line (PB), wherein - the width of the ski, measured perpendicular to the median longitudinal plane, at the front contact line (PA) is strictly less than the width of the ski measured at the rear contact line (PB) and the zone of minimum width (PIII) is further forward than the mid-shoe line (MC), characterized in that - the radius of curvature has a maximum value (RMAX) at a transverse line located strictly between the front contact line (PA) and the rear contact line (PB), - the ratio between the value of the maximum radius of curvature (RMAX) and the value of the radius of curvature at the front contact line is greater than 2.5, preferably greater than 3.

2. Alpine ski according to Claim 1, characterized in that the difference between the width at the front contact line (PA) and the width at the rear contact line (PB) is between 2 and 10 mm.

3. Alpine ski according to Claim 1, characterized in that the distance between the zone of minimum width (PIII) and the mid-shoe line (MC) is greater than 2 mm, preferably 5 mm.

4. Alpine ski according to Claim 1, characterized in that the distance between the zone of minimum width (PIII) and the mid-shoe line (MC) is lower or equal to 100 mm.

5. Alpine ski according to Claim 1, characterized in that the ratio between the value of the maximum radius of curvature (RMAX-AV) and the greater of the two radii of curvature (RMAX-AV, RMAX-AR) at the front and rear contact lines is greater than 4.

6. Alpine ski according to Claim 1, characterized in that the maximum radius of curvature (RMAX) is greater than 35 m.

7. Alpine ski according to Claim 1, characterized in that the variation of the radius of curvature (RC) of the sidecut according to the longitudinal position of the measuring point is a function whose second derivative with respect to said longitudinal position is positive for a longitudinal position between the rear contact line (PB) and the front contact line (PA).

8. Alpine ski according to Claim 1, characterized in that the transverse line where the radius of curvature is maximum is located approximately at the narrowest point of the ski (PIII).