Abstract:
A cross-country ski having an upwardly projecting longitudinal rib which laterally guides the shoe of the skier. For modifying its performance characteristics, the ski includes, on either side of the longitudinal rib, an auxiliary separate profile which is arranged to at least support the sole of the shoe. The separate profiles are affixed to the side surfaces of the rib.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a ski for cross-country skiing comprising a longitudinal rib projecting with respect to its top face. 
     2. Discussion of Background Information 
     Cross-country skis are already known which comprise a longitudinal rib on their top face. This longitudinal rib generally presents a trapezoidal cross section, in other words it is defined by a horizontal upper face and two inclined lateral faces and this rib of trapezoidal cross section joins the lower part of the ski which presents a rectangular cross section, of small height, of which the small sides constitute the edges of the ski. Due to the reduced height of these edges, such a cross-country ski slides more easily over the snow. Furthermore, the upper longitudinal rib contributes to the lateral guiding of the shoe mounted on the cross-country ski which is adapted to that end, due to the provision, in the sole, of a groove presenting in cross section a shape complementary of that of the rib of the ski. 
     SUMMARY OF THE INVENTION 
     The present invention relates to improvements in such a cross-country ski for the purpose of easily adapting its rigidity or its elastic response and of improving its technique, without notably increasing its weight. 
     To that end, this cross-country ski, comprising a longitudinal rib in its top part, is characterized in that it comprises, on either side of the longitudinal guiding rib and at least in the area where a shoe bears on the ski, an auxiliary separate profile fixed to the side face of the longitudinal guiding rib and lower than said rib, the separate auxiliary profile presenting a horizontal top surface on which bears the shoe sole. 
     The separate auxiliary profiles make it possible, due to a judicious choice of their material and shape, easily to modify the characteristics of a cross-country ski with longitudinal guiding rib, particularly concerning its suppleness and its response to stresses. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the present invention will be described hereinafter by way of non-limiting examples, with reference to the accompanying drawing, in which: 
     FIG. 1 is a partial view in perspective of a cross-country ski with longitudinal guiding rib on each side of which is fixed a separate auxiliary profile. 
     FIG. 2 is a view in vertical and transverse section, on a larger scale, made along line II--II of FIG. 1. 
     FIGS. 3 and 4 are views in vertical and transverse section of a cross-country ski of which the longitudinal guiding rib is flanked, on either side, by a separate elastic auxiliary profile. 
     FIGS. 5 to 8 are views in vertical and transverse section of various variant embodiments. 
     FIGS. 9 to 12 are schematic views in elevation illustrating the effect of elastic return ensured by each separate auxiliary profile. 
     FIG. 13 is a schematic view in elevation illustrating a cross-country ski in which the separate auxiliary profile extends solely under the ski shoe. 
     FIG. 14 is a schematic view in elevation of a cross-country ski in which the separate auxiliary profile extends virtually over the whole length of the ski. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 show a cross-country ski 1 which presents, in its top part, a longitudinal guiding rib 2 of trapezoidal cross section. However, this trapezoidal cross section is not limiting and it may present any other appropriate form, particularly polygonal or curved. In the embodiment shown in FIGS. 1 and 2, the cross section of the rib 2 is constituted by the superposition of two elementary sections in the form of isosceles trapezoid. The guiding rib 2 thus presents a horizontal top face 2a constituting the small base of the upper trapezoidal section, which is extended by two inclined lateral faces 2b, 2c. This upper trapezoidal section joins a lower trapezoidal section of which the upper small base corresponds to the large base of the upper trapezoidal section. The lower trapezoidal section comprises two lower inclined lateral walls 2d, 2e which are less inclined than the upper inclined lateral walls 2b, 2c. The two lower inclined lateral walls 2d, 2e join the vertical edges 1a, 1b, of small height, of the ski 1 which extend up to the sole 3 of this ski. 
     According to the invention, the cross-country ski 1 is provided, on either side of the longitudinal guiding rib 2, with a separate auxiliary profile 4, non-unitary with the rib 1 which is rigid in the case of the embodiment shown in FIGS. 1 and 2. This profile is fixed on the inclined lateral faces 2d, 2c of the rib 2 by any appropriate means, for example by gluing. The profile 4 presents a cross section in the form of a right-angled triangle and it comprises a horizontal top face 4a, a vertical outer face 4b and an inclined inner face 4c corresponding to the hypotenuse of the right-angled triangle. The triangular cross section of the separate auxiliary profile 4 is such that its vertical outer face 4b  lies in the plane of the edge 1a, 1b of the ski, that its inclined inner face 4c is applied on one of the lower inclined faces 2d, 2e of the rib 2 and that its top horizontal face 4a lies in the horizontal plane constituting the plane of separation of the two trapezoidal sections of the rib 2. 
     The separate rigid auxiliary profile 4 may be solid, as shown in the left-hand part of FIG. 2, or hollow as shown in the right-hand part of this Figure, on condition that, in the latter case, the wall of the profile is sufficiently thick to ensure the desired rigidity. The provision, on either side of the guiding rib 2, of separate rigid auxiliary profiles 4 makes it possible to modify as desired the overall characteristic of rigidity or of elasticity of the cross-country ski 1, depending on the desiderata. 
     FIG. 2 also shows the sole 5 of a ski shoe which is provided, in its lower face, with a longitudinal groove 6 capping the guiding rib 2. This sole 5 bears on the top horizontal faces 4a of the separate rigid auxiliary profiles 4 and the bottom of the groove 6 lies a little above the top face 2a of the rib 2, since the depth p of this groove 6 is slightly greater than the height h of the upper trapezoidal section 2a, 2b, 2c of the rib 2. 
     In the variant embodiment of the invention shown in FIGS. 3 and 4, the cross-country ski 1 bears, on either side of the longitudinal guiding rib 2, a separate auxiliary profile 7 made of supple and elastic material, for example rubber. Consequently, when the skier exerts a high pressure on his ski, at the moment of bearing on the ground, the elastic material of each separate auxiliary profile 7 is compressed by the sole 5 of the ski shoe, as is shown in FIG. 4. Such compression is rendered possible since the depth p of the groove 6 of the sole 5 is greater than the height h of the upper trapezoidal section 2a, 2b, 2c of the rib 2, so that the sole 6 may lower with respect to this rib, compressing the two separate auxiliary profiles 7. Such compression is therefore then translated, when the skier relaxes his pressure on the ski at the beginning of the advance stroke of this ski, by an elastic return of the material of the profile 7 to the relaxed state which thus contributes to the action of the skier&#39;s foot. 
     In the variant embodiment of the invention shown in FIG. 5, the longitudinal guiding rib 2 has a cross section presenting the form of a single isosceles trapezoid. In other words, the inclined lateral faces 2b, 2c extend downwardly, with the same inclination, as far as a short distance from the sole 3, and at that spot, they are joined to horizontal flanges 2f, 2g of small width, which extend outwardly as far as the edges 1a, 1b. Consequently, each separate auxiliary profile 8 presents a cross section in the form of a right-angled trapezoid defined by a horizontal top face 8a, a vertical outer face 8b lying in the vertical plane of the edges 1a, 1b, a horizontal lower face 8c in contact with the lower horizontal flange 2f, 2g and of the same width thereas, and an inclined inner face 8d, with the same inclination as the inclined lateral faces 2b, 2c of the rib 2, and in contact with the lower part of these faces. Each profile 8 is shown as being rigid in FIG. 5 and it may either be solid (left-hand part of FIG. 5), or hollow (right-hand part of FIG. 5). 
     FIGS. 6 and 7 show a variant embodiment in which the separate auxiliary profiles 9 have the same trapezoidal cross section as the profiles 8 but are made of a supple and elastic material, which allows their compression by the sole 5 of the shoe as shown in FIG. 7. 
     In the variant embodiment of the invention shown in FIG. 8, the cross-country ski comprises two separate auxiliary profiles 11, 12 of trapezoidal cross section, which are disposed on either side of the longitudinal guiding rib and are connected to each other. More particularly, the two separate auxiliary profiles 11, 12 constitute the end lateral parts of one and the same profile which comprises a top central part 13 of trapezoidal form, widening downwardly, which covers the top part of an inner profile 14 of likewise trapezoidal cross section, widening downwardly and joining the sole 3 of the ski. The two lateral profiles 11, 12 respectively comprise top horizontal faces 11a, 12a which join outer vertical faces 11b, 12b constituting the edges of the ski and which terminate in lower horizontal flanges 11c, 12c extending inwardly. The top trapezoidal central part 13 itself comprises a top horizontal face 13a and two inclined lateral faces 13b, 13c which respectively join the top horizontal faces 11a, 12a of the two lateral profiles 11, 12. 
     The inner profile 14 of trapezoidal cross section comprises a top horizontal face 14a on which is applied the top horizontal face 13a of the trapezoidal top central part 13, and two inclined lateral faces 14b, 14c on the upper parts of which are applied the inclined lateral faces 13b, 13c of the trapezoidal top central part 13. These lateral inclined faces 14b, 14c terminate, at their lower ends, in flanges 14d, 14e, extending outwardly and on which are applied the inner lower flanges 11c, 12c of profiles 11, 12. The volumes defined within the ski may be left empty or, on the contrary, they may be filled with a rigid, but light, material such as a foam. 
     FIGS. 9 and 10 illustrate the manner in which an elastic separate auxiliary profile, such as profile 7, yields and reacts when a ski shoe 15, which is articulated, with respect to the cross-country ski 1, about a horizontal and transverse axis 16, pivots about this axis, by raising the heel at the moment of bearing on the ski for advancing the other ski. FIGS. 9 and 10 show that the end 5a of the sole 5 penetrates slightly in the elastic separate auxiliary profile 7, during pivoting of the shoe 15 in anti-clockwise direction about axis 16, and that the elastic deformation of the profile 7 is translated by a return effort f tending to return the shoe 15 into horizontal position on the ski. 
     In the variant embodiment of the invention shown in FIGS. 11 and 12, the front part 5a of the sole 5 of the shoe is in abutment against an inclined face of a surelevated part 7a of the elastic separate auxiliary profile 7. Consequently, the movement of pivoting of the shoe 15, in anti-clockwise direction about the transverse axis 16, is translated by the penetration, by the end of the sole 5a, of the inclined face of the elastic surelevated part 7a which forms a slight bead 17, considerably exaggerated in FIG. 12, projecting with respect to the top surface, this bead 17 contributing to the elastic return of the shoe flat on the ski. 
     As may be seen in FIGS. 13 and 14, the separate auxiliary profile, whether it be elastic or rigid, may extend solely under the shoe 15 (FIG. 13), or virtually over the whole length of the cross-country ski 1 (FIG. 14), or over only part of this length. 
     In all the embodiments of the invention which have been described hereinabove, the two separate auxiliary profiles located respectively on the two sides of the longitudinal guiding rib 2, may be of the same type or possibly of different types, for example rigid on one side of the rib 2 and supple and elastic on the other.