ALPINE SKI WITH IMPROVED SIDECUT

Abstract

Alpine ski comprising a tip zone located at the front of the ski, a waist zone, and a tail zone 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 bordered by edges, a zone for mounting a boot, the middle of which, in the longitudinal direction, is located at a mid-shoe line (M.sub.C), and having a sidecut with: a front contact line (PA) defined as the line of contact between the gliding sole and a horizontal surface against which the sole is pressed when the waist is loaded, which is located furthest forward; a rear contact line (PB) defined as the line of contact between the gliding sole 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), characterized in that the width of the ski, measured perpendicular to the median longitudinal plane, at the front contact line (P.sub.A) is strictly less than the width of the ski measured at the rear contact line (P.sub.B) and in that the zone of minimum width (P.sub.III) is further forward than the mid-shoe line (MC).

Claims

1. Alpine ski comprising a tip zone located at the front of the ski, a waist zone, and a tail zone 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 bordered by edges, a zone for mounting a boot, the middle of which, in the longitudinal direction, is located at a mid-shoe line (M.sub.C), and having a sidecut with: a front contact line (P.sub.A) defined as the line of contact between the gliding sole and a horizontal surface against which the sole is pressed when the waist is loaded, which is located furthest forward, a rear contact line (P.sub.B) defined as the line of contact between the gliding sole and said horizontal surface, which is located furthest back, a line of greater front width (P.sub.I) located at or further forward than the front contact line (P.sub.A), a line of greater rear width (P.sub.II), located at or more rear than the rear contact line (P.sub.B), a zone of minimum width (P.sub.III) located in the waist zone, said sidecut having a variable radius of curvature between the front contact line (P.sub.A) and the rear contact line (P.sub.B), characterized in that the width of the ski, measured perpendicular to the median longitudinal plane, at the front contact line (P.sub.A) is strictly less than the width of the ski measured at the rear contact line (P.sub.B) and in that the zone of minimum width (P.sub.III) is further forward than the mid-shoe line (MC).

2. Alpine ski according to claim 1, characterized in that the difference between the width at the front contact line (P.sub.A) and the width at the rear contact line (P.sub.B) is between 2 and 10 mm.

3. Alpine ski according to claim 1, characterized in that the distance between the zone of minimum width (P.sub.III) and the mid-shoe line (M.sub.C) 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 (P.sub.III) and the mid-shoe line (M.sub.C) is lower or equal to 100 mm.

5. Alpine ski according to claim 1, characterized in that the radius of curvature has a maximum value (R.sub.MAX) at a transverse line located strictly between the front contact line (P.sub.A) and the rear contact line (P.sub.B), in that the ratio between the value of the maximum radius of curvature (R.sub.MAX) and the value of the radius of curvature at the front contact line is greater than 2.5, preferably greater than 3.

6. Alpine ski according to claim 5, characterized in that the ratio between the value of the maximum radius of curvature (R.sub.MAX_AV) and the greater of the two radii of curvature (R.sub.MAX-AV, R.sub.MAX-AR) at the front and rear contact lines is greater than 4.

7. Alpine ski according to claim 5, characterized in that the maximum radius of curvature (R.sub.MAX) is greater than 35 m.

8. Alpine ski according to claim 1, characterized in that the variation of the radius of curvature (R.sub.c) 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 (P.sub.B) and the front contact line (P.sub.A).

9. 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 (P.sub.III).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0030] The invention will be well understood, and its advantages and various other characteristics will become apparent, in the light of the following description of a few non-limiting exemplary embodiments, with reference to the appended schematic drawings, in which:

[0031] FIG. 1 is a schematic side view of a ski according to the invention, shown unloaded.

[0032] FIG. 2 is a side view of the ski of FIG. 1, shown loaded, with its underside pressed against a horizontal surface.

[0033] FIG. 3 is a schematic top view of the ski in FIGS. 1 and 2, showing the various dimensional parameters characteristic of the invention.

[0034] FIG. 4 is a diagram illustrating the variation of width measured along the ski of FIG. 3, as well as the variation of the radius of curvature.

[0035] Of course, the illustrations provided in the figures are schematic only, and certain proportions may differ from reality, for the sake of a better understanding of the invention.

DESCRIPTION OF EMBODIMENTS

[0036] For greater clarity, we define an Oxyz reference frame and xy, yx, and xz planes defined by the non-collinear x, y, and z vectors of the Oxyz reference frame. For greater simplicity, it will be considered that the forward direction corresponds to the longitudinal direction of the ski along the Ox axis, oriented from the waist towards the tip.

[0037] Generally speaking, a ski has dimensional parameters defined in accordance with ISO 62 89.

[0038] Thus, as illustrated in FIG. 1, the ski 1 has a tip zone 2 at the front and a tail zone 3 at the rear separated by the central zone 4, also referred to as the waist zone. When the ski 1 is placed on a horizontal plane 10, without being loaded, the camber it presents in the waist zone brings it into contact with this horizontal plane at two specific points 5; 6 front and back.

[0039] As illustrated in FIG. 2, when this ski 1 is loaded, i.e., when it is subjected to the weight of a user such that the camber of the waist zone 4 is counteracted, the gliding sole comes into contact with the horizontal plane 10 on a glide zone. This gliding zone 12 defined between two specific lines which are the front contact line P.sub.A, marking the rear border of the tip 2, and the rear contact line P.sub.B forming the front border of the tail zone 3.

[0040] Additionally, and as illustrated in FIG. 3, the ski 1 has a width which is variable from the tail 3 to the tip 2. This width, measured perpendicular to the median longitudinal plane along the Oy axis, has localized extremes. Thus, in the tail zone 3, the ski 1 has a maximum width at the point P.sub.II. In the embodiment illustrated in the figures, it should be noted that this point P.sub.II is behind the point P.sub.B corresponding to the rear contact line. On the other side of the ski, the latter has a maximum width at point P.sub.I, at a level located further forward than the front contact line P.sub.A.

[0041] The ski also has a minimum width in the waist zone, at point P.sub.III.

[0042] In some cases, the Applicant has found that a particular behavior can be observed when the ski width at the P.sub.B point of the ski, at the rear contact line, near the tail zone, is greater than the ski width at the P.sub.A point of the ski, at the front contact line, near the tip zone. More specifically, this difference in width (LP.sub.BLP.sub.A) can be between 2 to 10 millimeters and leads to a snow behavior that favors ski pivoting and is more tolerant of terrain imperfections.

[0043] As shown in FIG. 3, the ski has a zone in which the safety binding is designed to be fitted, to accommodate the user's boot. This zone is materialized by the dotted region 20 in FIG. 3, and essentially defined by the line M.sub.C corresponding to the mid-shoe. In particular, this point M.sub.C makes it possible to position the tail and toe of the binding symmetrically, relative to this point M.sub.C, to take account of the user's shoe size, or the implementation of a platform in which the toe and tail of the binding are adjustable in position.

[0044] The Applicant has observed the advantage of a configuration in which the zone of minimum width P.sub.III is located further forward than the mid-shoe line M.sub.C. In particular, this difference can be greater than 2 mm, or even greater than 5 mm, and preferably between 5 and 15 mm.

[0045] This parameter facilitates ski entry into the curve at the start of a turn.

[0046] The skis according to the invention have a particular geometry, especially with regard to the radius of curvature R.sub.C of the sidecut. In practice, this radius of curvature can be measured from the variation in the width of the ski, measured in the longitudinal direction Ox. Thus, from a ski width profile reading along the Ox axis, it is possible to calculate the curvature, and the radius of curvature (which is the inverse of the curvature) to produce a curve as shown in FIG. 4. More precisely, the second derivative of the ski width curve is used to obtain the curve giving the curvature of the ski along the sidecut. Of course, other practical methods can be implemented to calculate this radius of curvature, in particular by using mechanical devices which are moved along the sidecut. By approximating the measured sidecut with a polynomial of degree three, for example, it is possible to obtain the curve of the radius of curvature along the ski by deriving this polynomial twice. Using empirical calculations based on the coordinates of three gliding points moving along the sidecut, it is also possible to calculate the radius of curvature.

[0047] In accordance with the invention, the radius of curvature has a specific variation so that it has a maximum value R.sub.MAX located close to, or even coincident with, the point of least width P.sub.III. The value of the maximum radius of curvature is particularly high, greater than 35 m, or even 50 m, preferably between 50 and 80 m. In particular, this maximum value can be used to adjust the ski's degree of grip.

[0048] In addition thereto, and as illustrated in FIG. 3, the radius of curvature is significantly smaller as one moves towards the ends of the ski. St the ends of the ski, at points P.sub.A and P.sub.B, the radii of curvature are between 5 and 20 m, preferably between 10 and 20 m.

[0049] It can be seen in FIG. 4 that the minimum values of the radius of curvature at the front R.sub.MAX-AV and at the rear R.sub.MAX-AR are much lower than the value of the maximum radius R.sub.MAX, in a ratio of at least 2.5 or even preferably greater than 3, even 4.

[0050] In addition thereto, the evolution of the radius of curvature is also specific to skis conforming to the invention, since as can be seen in FIG. 4, the second derivative of the radius of curvature calculated along the O.sub.X axis is such that it is always positive, meaning that the closer you get to the point where the radius of curvature is maximum, the faster this radius of curvature increases.

[0051] The geometry of the skis according to the invention is particularly advantageous for its performance qualities on snow while remaining easy. More precisely, these skis offer an ease of entry into turns, a distribution of the support pressure across the entire length of the ski which allows avoiding points of over-gripping. Such skis have a narrower tip, which is easier to handle because it doesn't produce accidental gripping at the front.