EP0780143A1 - Snowboard with stiffening device - Google Patents

Abstract

The ski or snow-board (1) has a lower sliding surface and an upper surface with boot fastening clamps (3,4) and a regulator for varying the rigidity of the ski/snow-board. The regulator comprises an upper elongated platform (2) carrying the clamps, fixed or hinged to the board by its forward end, having an intermediate support (12) which is either fixed or sliding, an elastic block, and a pair of cams (14) at the rear end. The cams are located on the underside of the platform and the upper surface of the board and have interacting sloping surfaces (15,17) which form an angle of 30 - 60 degrees, and preferably 45 degrees, with the board's upper surface. In a variant of the design one of the cams can be a cylindrical roller, turning about an axis perpendicular to the board's median lengthwise plane, and the cams can be surfaced with a friction reducing material, such as PTFE.

Description

Technical area

The invention relates to the field of snow sliding sports. It relates more particularly to gliding boards equipped with a device interposed between the binding and the top of the board making it possible to adapt, interactively, the characteristics of the board to the different positions and intensities of the pulse forces observed during of the practice of sport, especially during the making of a turn.

Subsequently, the invention will be described in its more particular application to alpine skiing, without it being necessary to exclude from the scope of the invention the other snow sliding sports such as monoskiing or snowboarding.

Previous techniques

The invention in particular aimed at optimizing the behavior of a ski when making a turn, it is necessary beforehand to specify the different phases and the position of the forces transmitted by the skier to the ski during a turn. Very schematically, a turn can be broken down into three essential phases, namely the initiation, driving and exiting of the turn.

During the initiation phase of the turn, the skier carries his body weight towards the inside of the turn and towards the front. The ski must then bend to register its internal edge in a curve. To decrease the radius of curvature of this trajectory, the skier's impulse, that is to say the force he exerts on the ski, must be greater than to make a turn with a large radius. It has been observed that the impulse exerted can reach a force corresponding to five to eight times the weight of the skier. To facilitate the curvature of the ski during this triggering phase, the ski must be flexible enough and the application of the skier's load on the ski must be practically punctual, in order to obtain short ski behavior.

During the driving phase of the turn, the skier's position recedes so that the weight of his body is applied practically at the level of the middle of the boot. In this phase, the ski maintains its radius of curvature.

Finally, at the end of the turn, the skier moves his body weight backwards, so the skier's support area on the ski moves in the direction of the heels of the boots. During this phase, it is preferable to have a stiffer ski, behaving like a ski of greater length in order to improve its stability. In this phase, the weight of the skier must be distributed over the maximum length of the ski.

It is therefore understandable that, ideally, the ski should behave like a short and very flexible ski when initiating and driving the turn, then transform into a long and stiff ski for the driving phase.

Document FR-A-2 702 386 of the applicant describes a hydraulic device allowing, depending on the front or rear location of the skier's thrust, the modification of the general stiffness of the ski. Although satisfactory and giving appreciated results, this solution needs to be implemented within the thickness of the ski, which requires relatively complex operations which are economically unprofitable.

FR-A- 2 684 885, FR-A-2 686 798, FR-A-2 686 799, FR-A-2 690 079 and FR-A-2 713 945 have also been proposed devices to modify the natural pressure distribution of a ski on its sliding surface. These devices are installed under the sole of the boot, between the toe and the heel of the binding and allow a system of arms, levers and rockers actuated during the booting of the shoe to exert tension on the ski. Unfortunately, this device requires a large number of parts which have particularly stressed articulation axes, and therefore fragile especially under the conditions of use (humidity and cold) and moreover generating mechanical play. In addition, they do not dynamically change the stiffness of the ski depending on the position of the skier. They practically do not vary the stiffness of the ski in use, depending on the location of the supports exerted by the skier. These devices modify the stiffness of the ski and its camber as soon as the boot is placed in the binding, only by applying the load on the heels of the boots.

The problem which the invention proposes to solve is to provide a ski whose stiffness changes dynamically during the different phases of the turn. The aim is to give the ski a behavior equivalent to that of a short and flexible ski during the forward presses at the start of the turn, and alternatively the behavior of a long, stiff ski when the rear supports are present for the terminal phase of the turn.

Statement of the invention

The invention relates to a sliding board, namely for example an alpine ski, a cross-country ski, a monoski or a snowboard, having a lower sliding face and an upper face intended to receive in the skate area, a binding able to secure the user's shoe to the board, the board being equipped at the level of the shoe with a stiffening device intended to modify the stiffness of the board under the effect of a push exerted by the user towards the face top of the board.

• une plateforme supérieure allongée, destinée à recevoir la fixation sur sa face supérieure, l'extrémité avant de ladite plateforme étant solidaire d'un point lié à la surface extérieure de la planche ;
• un plot intermédiaire rigide, indéformable et de hauteur fixe, disposé entre la face inférieure de la plateforme et la face supérieure de la planche, séparant la plateforme en zone avant et zone amère.
• des moyens destinés à bander au moins une partie de la planche sous l'action d'une poussée verticale exercée dans la zone arrière de la plateforme.

The gliding board according to the invention is characterized in that the stiffening device comprises:

• an elongated upper platform, intended to receive the fixing on its upper face, the front end of said platform being integral with a point linked to the outer surface of the board;
• a rigid, non-deformable intermediate pad of fixed height, disposed between the underside of the platform and the top face of the board, separating the platform in the front zone and the bitter zone.
• means intended to bandage at least part of the board under the action of a vertical thrust exerted in the rear zone of the platform.

In other words, the board receives a platform interposed between the binding and the top of the board, this platform acting on the board to generate a different behavior depending on whether the user's supports are located towards the front or towards the front. 'back. Thus, when the supports are directed forwards, the platform serves as a simple raising intermediary and transmits the forces on the one hand, via the front fulcrum and on the other hand, via the intermediate stud located substantially at the level of the arch of the shoe. The skier's load is thus distributed over a short area and could be assimilated to a point load.

On the other hand, during the supports located behind the intermediate stud, the platform transmits, in addition to a load perpendicular to the sole, two opposite longitudinal components resulting in a tensioning of the ski between the two support points of these components, and therefore an increase in the stiffness of the ski in this area. So in this phase, the load of the skier is then distributed over a relatively longer area than during the previous phase.

In other words, in summary, when the rear supports, the ski behaves more stiffly than during the front supports.

Regarding the intermediate pad, it is necessarily rigid to constitute a support area of the platform. In a first embodiment, it is integral with the upper face of the board and the lower face of the platform slides on the upper face of the stud. In a second embodiment, the stud is integral with the underside of the platform and the underside of the stud can slide on the upper face of the board. Typically, it is located substantially at the middle of the shoe, that is to say in the border area between the front and rear supports.

To resolve the problem of balancing the behavior of the platform as a function of the precise location of the front and rear supports, the intermediate assembly includes means for adjusting the stud in the longitudinal position relative to the board and / or the platform.

In a first embodiment of the invention, the means intended to bandage part of the board consist of a set of cam surfaces disposed respectively under the underside of the platform and on the top face of the board, said surfaces of cams being oriented downwards and towards the front of the board, so as to cause the support point at the front of the platform (A) to separate from the support point for the cams (B) , under the effect of a thrust perpendicular to the surface of the board, exerted in the rear area of the platform.

Thus, during the rear supports, the facing cam surfaces slide relative to each other, which causes, given their inclination and the rigidity of the platform, the slight separation of the anchor point of the cam integral with the ski (B) relative to the fulcrum of the front end of the platform (A). In this way, the skate area of the ski is bandaged or stretched thanks to the platform.

The cam surfaces therefore have the function of transforming the vertical displacement generated by the impulse given by the skier when the turn is initiated into horizontal components generating tension under the skate. This pushing force therefore results in an increase in the initial stiffness of the ski in the skate area and therefore a feeling of longer skiing because the load is distributed over the length of the skate.

Advantageously in practice, at least one of the cam surfaces is formed by an inclined slope whose inclination relative to the upper face of the board is between 30 and 60 degrees, more precisely in the vicinity of 45 degrees.

In another advantageous embodiment, one of the cam surfaces consists of a cylindrical roller with an axis of revolution perpendicular to the median longitudinal plane of the board.

In a more sophisticated form of the invention, this roller is rotatably mounted relative to its axis of revolution to reduce the effects of friction. Furthermore, still to reduce the phenomena of friction, the facing cam surfaces are covered with a coating intended to reduce the coefficient of friction, typically with a layer of polytetrafluoroethylene.

To avoid excessive travel, the stiffening device includes a stop capable of limiting the movement of the rear end of the platform upwards and backwards. Thus, during the front presses, the platform tends to lift in the rear part. This characteristic stop therefore prevents the rear end of the platform from being raised excessively.

In a preferred form of the invention, the stiffening device comprises a strip of visco-elastic material interposed between said stop and the rear end of the platform, to absorb these displacements.

In a variant, an elastic return element can be housed under the rear part of the platform, between the top of the board and the lower part of the platform. This elastic element can be a mechanical spring (coil or leaf) or a stud made of elastic material (rubber for example).

The plate constituting the platform must be rigid enough to transmit, without buckling, the longitudinal forces intended to tighten the pad area of the board. This plate can be either metallic, or a composite material reinforced with glass fibers, carbon or Kevlar ®, or reinforced plastic material.

In a second embodiment of the invention, the means intended to bandage part of the board consist of an arm situated at the rear of the platform, the front end of which is articulated at the rear of the platform, the rear end of the arm supported on a fixed point on the upper face of the board, and pushing it back, under the effect of a vertical thrust exerted in the rear area of the platform.

The fixed fulcrum of the rear end of the arm may be either a notch located in the upper part of the ski, or a stop provided or attached to the ski.

In other words, the platform has an articulated rear extension such that, during rear supports, the part of the platform located between the intermediate stud and its rear end flexes, which has the effect of opening the angle a formed by the end of the platform and the arm, and therefore to separate said fixed point (A) corresponding to the front end of the platform, from the rear fixed point (C) linked to the upper surface of the ski, which causes the setting energized skate area.

In an advantageous form, the rear end of said arm is articulated on the upper face of the board, in particular by means of an intermediate piece.

In a third embodiment, the means intended to bandage part of the ski also comprise a second arm forming a compass with the first, the front end of this second arm bearing on a second fixed point (D) of the upper face of the board, these two fixed points being distant from each other under the effect of a vertical thrust exerted in the rear area of the platform.

In other words, the rear part of the platform rests on a compass forming an flying buttress which causes, when it is crushed during the rear support phases, the tensioning of the skid area between the points of supports (C) and (D).

Brief description of the figures

The manner of carrying out the invention as well as the advantages which result therefrom will emerge clearly from the description of the embodiments which follows in support of the appended figures in which:

Figure 1 is a side view of a first embodiment of the invention shown in the rest position.

Figure 2 is a side view of the same embodiment shown during front presses.

Figure 3 is a side view of the same device shown during rear support.

Figure 4 is a side view of a first alternative embodiment of the invention.

Figure 5 is a side view of another variant concerning the front articulation of the platform.

Figure 6 is a side view illustrating an alternative embodiment in which one of the cam surfaces is formed by a roller.

Figure 7 is a side view of a second embodiment of the invention shown in the rest position.

Figure 8 is a side view of the same device shown during rear support.

Figures 9 and 10 are side views of a third embodiment of the invention in two different forms.

For the sake of simplification, it will be considered subsequently that the board described is placed on a horizontal plane, so that the direction of the impulses exerted by the skier corresponds to the vertical.

Ways to realize the invention

As already said, the invention relates to a gliding board, in particular a ski, which comprises a device allowing the stiffening of said ski as a function of the front or rear position of the thrust exerted by the skier. As already seen, several architectures allow to achieve the desired result.

In all of its embodiments, the invention is in the form of a platform (2) intended to receive at the front, the stop (3) and at the rear, the heel piece (4) for fixing the boot and which is placed substantially at the level of the skate area of the ski (1).

As already mentioned, the invention relates to a sliding board, but it will be described below in detail for its application to an alpine ski.

First way of carrying out the invention

As can be seen in FIG. 1, the intermediate stiffening device according to the invention is in the form of an elongated platform (2) which sees its front end (10) secured to the upper face (5) of the ski ( 1), with the appropriate curvatures (11).

The platform (2) has in its central region, substantially at the middle of the boot, a rigid intermediate pad (12), interposed between the platform (2) and the upper face (5) of the ski. As already said, this stud (12) can be fixed on the upper face (5) of the ski and support the sliding of the lower face of the platform, or vice versa.

In an advantageous form, it is possible to adjust the longitudinal position of this stud (12) as a function of: the total length of the platform (2), its position on the ski, the position of the bindings on the platform, and the front / rear distribution of the supports (F1, F2).

The lower face (13) of the platform (2) receives, in the rear area, a wedge (14) which has a sloping face (15) oriented forward and downward.

This sloping wedge (14) faces a second sloping wedge (16), fixed on the upper face of the ski. Symmetrically, the slope (17) of this second wedge (16) is also oriented downwards and towards the front of the ski.

The upper face (5) of the ski receives a stop (20) forming a square whose horizontal branch (21) covers the rear end (22) of the platform (2) in order to limit the upward movement.

Typically, at rest, that is to say when the platform supports only the weight of the skier excluding any impulse, the distance (e ₁ ) between the upper face of the platform (2) and the branch horizontal (21) of the square is 2 millimeters, while the front face (24) of the vertical branch (23) of the square is distant (d ₁ ) by about 5 millimeters from the rear end (22 ) of the platform (2).

In a variant not shown, it is possible to have in this rear zone between the rear end of the platform (22) and the stop (20), a strip of visco-elastic material intended to make the movement progressive.

In an alternative embodiment of this first embodiment, the front end (10) of the platform (2) is articulated on an intermediate piece (18) itself fixed on the upper face of the ski (see FIG. 4) .

In another variant illustrated in FIG. 5, the front end of the platform has vertical extensions (25) which are articulated directly on the board, in particular at the edges thereof.

The invention is not limited to the cam surfaces described in FIGS. 1 to 5, but these can of course take any other advantageous form, in particular that of a cylindrical roller (26) rolling on a cam 16, such as illustrated in figure 6.

Furthermore, the cam surfaces in contact can advantageously be covered with a surface which facilitates sliding and reduces the coefficient of friction.

In addition, it may be advantageous to insert between the rear part of the platform (2) and the upper face (5) of the ski, a stud (29) made of elastic material allowing the device to return to the initial position.

The operation of this first embodiment is as follows.

The rest position, corresponding to the state in which the platform (2) is under the simple effect of the weight of the skier is illustrated in Figure 1. We see in Figure 2 the deformations generated by a localized pulse (F1) at the front which can reach the equivalent of six to seven times the weight of the skier.

In this case, the front part of the platform (2) rests on its articulation at the front (10), and on the intermediate stud (12) in the middle part. In this way, the front supports (F1) are transmitted by these two connecting zones (10, 12) from the platform (2) to the ski (1).

Subsequently, during the rear supports (F2), the rear part of the platform (2) sees the two sloping wedges (14, 16) sliding relative to one another. Given the downward and forward orientation of the two slopes (15, 17), the stiffness of the platform (2) causes tension between the points (A) and (B) corresponding to a bandage of the ski skate area. In this way, the stiffness of the platform (2), which of course is associated with the stiffness of the boot, is added to the stiffness of the ski (1) in the skate area. Thus, the behavior of the board corresponds to that of a longer ski, which allows, as expected, better stability at the end of the turn.

At the rear wedge (20), the bending of the platform (22) consecutive to the front supports (F1) results in an approximation (e ₂ <e ₁ ; d ₂ <d ₁ ) of the rear end (22 ) of the platform (2) respectively of the horizontal part (21) and the vertical part (24) of the wedge (20).

On the other hand, when the rear supports (F2), the rear end (22) of the platform tends to descend and move away (e ₃ > e ₁ ; d ₃ > d ₁ ) from the stop (20).

Second way of carrying out the invention

Figures 7 and 8 illustrate an embodiment of the invention in which the platform has in its rear area a joint (30) with an arm (31) forming an extension towards the rear. The rear part (32) of this arm comes to bear on a transverse stop (33) integral with the upper face (5) of the ski. Thus, during the rear supports (F2), the bending of the rear of the platform (2) tends to open the angle a (a ₂ > a ₁ ), therefore the rear end (32) of the arm pushes the stop (33). Thus, the area of the pad is banded between said transverse stop (33) (point C) and the point before hooking (10) (point A) of the platform (2) on the ski (1).

Of course, it is not going beyond the scope of the invention to replace this transverse stop (33) with an equivalent articulation chappe.

Third way of carrying out the invention

It is also possible to power up the ski only in a reduced area adjacent to the skate. The embodiment described in Figure 9 shows a platform (2) under the rear area (45) of which is disposed an arc (40) formed by a spring leaf. The front (41) and rear (42) ends of this leaf spring (40) come to bear on two transverse stops (43, 44) disposed respectively in front and behind these ends.

In this way, when the rear supports (F2), the rear end (45) of the platform comes to crush this leaf spring (40), the front (41) and rear (42) ends of which push the transverse stops (43, 44), which causes the ski to be tensioned in the zone between said stops (43, 44).

Of course, it is not going beyond the ambit of the invention to replace this leaf spring by a set of arms forming a compass, possibly articulated on the rear part of the platform (see FIG. 10).

It appears from the above that the intermediate stiffening device installed on the gliding boards according to the invention advantageously makes it possible to dynamically modify the stiffness of the ski as a function of the variation in the position of the skier's supports.

Thus, when the corners are triggered, when the supports are located at the front, the ski retains its natural flexibility. On the other hand, at the end of turns, when the supports are rather oriented towards the rear of the ski, the device according to the invention allows the ski skid to be tensioned, therefore its stiffening.

This increase in stiffness allows for easier driving and a more stable turn termination, which is more comfortable.

Claims (18)

Gliding board (1) having a lower sliding face and an upper face (5) intended to receive in the skate area a binding (3, 4) capable of securing the user's shoe to the board (1), the board (1) being fitted at the level of the pad with a stiffening device intended to modify the stiffness of the board under the effect of a push exerted by the user towards the upper face of the board, characterized in that the device stiffener includes: - an elongated upper platform (2), intended to receive the fixing (3, 4) on its upper face, the front end (10) of said platform being integral with a point linked to the structure (5) of the board ; - An intermediate pad (12), rigid, non-deformable and of fixed height, disposed between the underside of the platform (2) and the upper face (5) of the board; - Means intended to bandage at least part of the board (1) under the action of a vertical thrust (F2) exerted in the rear area of the platform (2). Gliding board according to claim 1, characterized in that the front end (10) of the platform is fixed to the upper face of the ski. Gliding board according to claim 1, characterized in that the front end (10) of the platform is articulated with respect to the upper face of the ski. Gliding board according to claim 1, characterized in that the rigid stud (12) is integral with the upper face (5) of the board and in that the lower face of the platform can slide on the upper face of the stud (12 ). Gliding board according to claim 1, characterized in that the pad (12) is integral with the underside of the platform, and in that the underside of the pad (12) can slide on the top face (5) of the board. Sliding board according to one of claims 1 to 5, characterized in that it comprises means for adjusting the longitudinal position of the pad relative to the board and / or the platform. Gliding board according to one of claims 1 to 6, characterized in that the intermediate pad (12) is disposed substantially at the level of the middle of the user's shoe. Gliding board according to one of claims 1 to 7, characterized in that it comprises an elastic return element (29) interposed between the upper face of the board and the lower face of the platform, behind the level of the pad intermediate (12). Gliding board according to one of claims 1 to 7, characterized in that the means intended to bandage a part of the board consist of a set of cams (14, 16) disposed respectively under the underside of the platform (2 ) and on the upper face (5) of the board, said cams having surfaces (15, 17) oriented towards the bottom and towards the front of the board, so as to cause the support point to move apart. 'front (10) of the platform (point A) relative to the fulcrum of the cams (point B), under the effect of a thrust perpendicular to the surface of the board, exerted in the rear area of the platform . Gliding board according to claim 9, characterized in that at least one of the cams (14, 16) is constituted by an inclined slope (15, 17). Gliding board according to claim 9, characterized in that the inclination of the inclined slope (15, 17) relative to the upper face of the board is between 30 ° and 60 °, more precisely in the vicinity of 45 °. Gliding board according to claim 9, characterized in that one of the cam surfaces (15, 17) consists of a cylindrical roller (26) with an axis of revolution perpendicular to the median longitudinal plane of the board. Gliding board according to one of claims 1 to 12, characterized in that the cam surfaces (15, 17) are covered with a coating intended to reduce the coefficient of friction. Gliding board according to one of claims 1 to 12, characterized in that it comprises a stop (20) capable of limiting the movement of the rear end (22) of the platform upwards and backwards. Gliding board according to claim 13, characterized in that it comprises a strip of visco-elastic material interposed between the stop and the rear end of the platform. Gliding board according to one of claims 1 to 6, characterized in that the means intended to bandage part of the board consist of an arm (31) located at the rear of the platform, the front end of which ( 30) is articulated at the rear of the platform (2), the rear end (32) of the arm bearing on a fixed point (33) of the upper face of the board, and pushing it back under the effect of a vertical thrust (F2) exerted in the rear area of the platform. Gliding board according to claim 16, characterized in that the rear end (32) of the arm is articulated on the upper face of the board. Gliding board according to one of claims 16 or 17, characterized in that the means intended to bandage part of the platform also comprise a second arm forming a compass (40-51) with the first, the front end (41- 51) of this second arm bearing on a second fixed point (43-53) of the upper face (5) of the board, these two fixed points being spaced apart from one another under the effect of a thrust vertical (F2) exerted in the rear area of the platform.

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