EP0639391A1 - Ski provided with variable elastic dampers in both sides of the binding - Google Patents

Abstract

The invention relates to a ski consisting of an elongate beam (1) having a curved part (2) of length (LC) between a front contact line (20) and a rear contact line (21); the said central part comprising a region for mounting the bindings (5). The ski comprises two dampers (6, 7) arranged in the central part (2) and each on either side of the said mounting region (5). One of the ends (60, 70) of each damper is connected to the beam by a complete linkage (8); the other end (61, 71) is connected by a partial linkage means which is free to translate along a longitudinal direction and is composed of an elastic and/or viscous element (90, 91) which opposes the longitudinal displacement of the said damper; the part (62, 72), of length (IT1, IT2) of each damper between the two linkages being left free, at least in translation, with respect to the beam; the ratio (IT1) of the front damper (6) to (IT2) of the rear damper (7) lying between 1.5 and 2.5 and (IT1 + IT2)/LC lying between 0.15 and 0.25. The invention is an improvement to known ski damping devices. <IMAGE>

Description

The present invention relates to an improved ski, such as an alpine ski, a cross-country ski, a monoski or a snowboard.

It is known to make the ski body thanks to a more or less flexible structure.

We already know different types of ski and there are many variations. These consist of an elongated beam whose front end is curved upwards to form a spatula, the rear end also being more slightly to form the heel. Current skis generally have a composite structure in which different materials are combined so that each of them intervenes optimally, taking into account the distribution of mechanical stresses when using the ski. Thus, the structure generally comprises peripheral protection elements, internal resistance elements to resist the flexural and torsional stresses, and a core. These elements are assembled by gluing or by injection, the assembly generally being carried out hot in a mold having the final shape of the ski, with a front part strongly raised in tip, a rear part slightly raised in heel, a central arched part. .

Current skis have a certain number of drawbacks, and in particular that of insufficient behavior in response to stresses due to vibrations or flexing of the ski. Indeed, the persistent vibrations cause a loss of grip and therefore, poor skiing.

It is therefore important to provide a suitable response opposing this type of solicitation.

Application FR-A-2 675 392 of the applicant relates more particularly to a damping device for skiing consisting of at least one flexible blade connected to the ski by a rigid connection means and at least one flexible connection means; said means being spaced longitudinally from each other on said blade.

Application FR-A-2 521 272 by the applicant relates to another damping device in which the flexible connection means is replaced by a friction means.

In FR 92 09734 unpublished application of the applicant, the friction means is of the viscous type.

• la masse de la partie avant du ski est plus importante que celle de la partie arrière ;
• l'amplitude et l'intensité des sollicitations subies par l'avant du ski sont plus importantes que celles subies par l'arrière ;
• en fonction du type de ski pratiqué (grande courbe ou virages serrés), les besoins en terme de stabilité ou de maniabilité de la partie avant et de la partie arrière sont différents.

Compared to this prior art, the present invention is an improvement which takes account of the facts that:

• the mass of the front part of the ski is greater than that of the rear part;
• the amplitude and intensity of the stresses experienced by the front of the ski are greater than those experienced by the rear;
• Depending on the type of ski practiced (large curve or tight turns), the needs in terms of stability or maneuverability of the front part and the rear part are different.

In addition, the present invention is not limited to a vibration damping device as the prior art teaches. Indeed, for certain types of ski, certain stresses at the front and / or at the rear do not necessarily require dissipation but on the contrary a return force without cushioning to provide more maneuverability. On the contrary, for other skis, it will be necessary to provide a response in terms of damping to increase stability and precision at high speed.

The present invention therefore proposes to provide an improvement to the skis of the prior art while taking more account of the needs of the skier. For this, the invention relates to a ski consisting of an elongated beam having a central arched length LC length between a front contact line and a rear contact line; a front part raised in tip and a rear part less raised in heel; said central part comprising an area for mounting the fasteners corresponding to the standardized area. The ski comprises two transmitters arranged in said central part and each on either side of said area for mounting the bindings; one end of each transmitter being connected to the beam by a complete connection; the other end of each transmitter being connected to the beam by a partial connection means, free in translation in a longitudinal direction, composed of an elastic and / or viscous element which opposes the longitudinal movement of said transmitter; the length part (l _T1, l _T2 ) of each transmitter between the two connections being left free, in translation at least, relative to the beam; the ratio of the free length (l _T1 ) of the front transmitter to the free length (l _T2 ) of the rear transmitter being between 1.5 and 2.5; and the ratio (l _T1 + l _T2 ) on LC being, for its part, between 0.15 and 0.25.

Because the ski is fitted with transmitters, in the ratios of the chosen length, on either side of the mounting area, it is possible to obtain control of the dynamic deformation of the front part and the rear part of the ski. ski, and thus a balance and stability set.

To be effective, each transmitter must cover an "active" area of the ski, that is to say that between the contact line (front or rear) and the mounting area which corresponds to the free part in contact with the snow. .

The role of each transmitter is to oppose the stresses which have the effect of taking off each "active" part of the snow surface by damping effect and / or by elastic return effect as the case may be.

doit être compris dans les limites définies précédemment.To be effective, the overlap length of the transmitters must be sufficient but suitable for each use. For this, the report ${\text{(l}}_{\text{T1}}{\text{+ l}}_{\text{T2}}\text{) / LC}$

must be within the limits defined above.

According to another characteristic of the invention, the end of each transmitter connected by a complete link is located on the side in the direction of the front or rear part, the other end being located on the side in the direction of the mounting area. Therefore, the stresses of large amplitude at the ends are picked up by the fixed end of the stiffener, transmitted by the free part then "treated" at the end of the transmitter provided with the partial connection means of the elastic and / or viscoelastic type. in a region close to that where the weight of the skier is distributed, therefore more stable.

According to another important characteristic, the distance (d1) separating the front end of the front transmitter from the front contact line is between 0.18 LC and 0.25 LC.

Similarly, the distance (d2) separating the rear end of the rear transmitter from the rear contact line is between 0.16 LC and 0.21 LC.

These two characteristics define the fixing area of the transmitter in each free part of the ski with respect to each contact line. Too close a proximity of the transmitters to the contact line can be harmful since this leads to too controlled ski handling. It becomes difficult to handle and taking turns requires greater effort on the part of the skier. Conversely, too great a distance of the fixed point of the transmitter from the contact line produces the opposite harmful effect. The ski is not very "driven", that is to say that it loses stability at high speed and the skier has difficulty in keeping the ski on the targeted trajectory. On the other hand, when a damping effect is sought, this is all the weaker as the fixed point is distant from the contact line.

More particularly, for a “special” slalom type ski, we will look for a distance (d1) (at least) close to its upper limit.

Conversely, for a "giant" slalom ski, we will look for a distance (d1) (at least) close to its lower limit.

According to another additional characteristic, under bending stress, the displacement (Δ1) of the rear end of the front transmitter relative to the beam is greater than the displacement (Δ2) of the front end of the rear transmitter; so that the ratio (Δ1 / Δ2) is between 1.2 and 2.5.

According to another advantageous characteristic, the stiffness K1 of the elastic and / or viscous means of the front transmitter is greater than the stiffness K2 of the elastic and / or viscous means of the rear transmitter so that the ratio K1 / K2 is between 1.2 and 5.

The partial connecting means can be constituted by different means depending on the desired effect.

The choice of these means is not limiting, but advantageously, the following selected cases can be provided:
The partial connection means consists of an interface layer of elastic or viscoelastic material connecting, at least, the underside of the end of each transmitter above the beam in order to work in shearing by the longitudinal displacement of said end relative to the beam. The choice of such a solution has the advantage of limiting the size of the device, in particular the height of the latter relative to the beam of the ski. It is, on the other hand, particularly simple in its implementation, economical, and reliable in operation. The viscoelastic properties of the material providing the interface make it possible to dissipate the energy transmitted by the device.

The partial connection means may also consist of a spring / stop assembly working on compression. This system, unlike the previous one, does not dissipate the energy transmitted but provides an elastic response which tends to oppose the deformation of the front or rear part of the ski.

According to another solution, the spring can be replaced by an elastic or viscoelastic buffer.

Finally, the spring or elastic or viscoelastic buffer assembly can also be provided for working in traction.

• la figure 1 est une vue longitudinale d'un ski selon l'invention ;
• la figure 2 est une vue de dessus du ski de la figure 1 ;
• la figure 3 est une vue du ski des figures 1 et 2 en position fléchie ;
• la figure 3a montre un détail de l'extrémité avant du transmetteur avant, à plus grande échelle ;
• la figure 3b montre un détail de l'extrémité arrière du transmetteur arrière, à plus grande échelle ;
• la figure 4 est un exemple de courbe $\text{F=f(Δ)}$
  
  pour un matériau du type viscoélastique ;
• la figure 5 illustre une variante de la figure 1 ;
• la figure 6 montre un détail de la figure 5 ;
• la figure 7 montre un détail de la figure 5 selon une variante ;
• la figure 8 montre un détail de la figure 5 selon une autre variante.

Other characteristics and advantages of the invention will emerge from the description which follows with reference to the appended drawings which are given only by way of nonlimiting example.

• Figure 1 is a longitudinal view of a ski according to the invention;
• Figure 2 is a top view of the ski of Figure 1;
• Figure 3 is a view of the ski of Figures 1 and 2 in the bent position;
• Figure 3a shows a detail of the front end of the front transmitter, on a larger scale;
• Figure 3b shows a detail of the rear end of the rear transmitter, on a larger scale;
• Figure 4 is an example of a curve $\text{F = f (Δ)}$
  
  for a material of the viscoelastic type;
• Figure 5 illustrates a variant of Figure 1;
• Figure 6 shows a detail of Figure 5;
• Figure 7 shows a detail of Figure 5 according to a variant;
• Figure 8 shows a detail of Figure 5 according to another variant.

The ski according to the invention comprises an elongated beam (1) having its own distribution of thickness, of width and therefore its own stiffness.

The beam can be divided into several separate parts; a central arched part (2) of length LC, delimited by a front contact line (20) and a rear contact line (21). When the ski is at rest, that is to say when it is not loaded by the mass of the skier, the ski rests according to the two contact lines (20, 21). When the ski is loaded, the contact between the lower surface of the ski and the snow is made between the contact lines (20, 21) on a surface of length LC, due to the cancellation of the camber of the ski. The beam also includes a front tip portion (3) beyond the front contact line (20). This part is strongly raised, as known per se. Below the rear contact line (21) extends a rear part of the heel (4) which is less raised.

The central part (2) includes an area for mounting the fasteners (5) corresponding to the so-called "standardized" area. In the case of alpine skiing, the standardized area is defined by standard IS0 8364. In cross-country skiing, the standard is DIN-IS0 9119. Finally, in the field of snowboarding, the standard is being development (IS0 10958).

In Figures 1 and 2, the beam (1) of the ski is overcome in its central part (2) and on either side of the mounting area (5) by two transmitters (6, 7). The term “transmitter” refers to any elongated element which is relatively flexible so as not to provide excess stiffness locally, but which is sufficiently resistant to buckling to be able to fulfill its function of transmitting stresses from one end to the other. The buckling resistance function can be partially fulfilled by additional guiding means in the free part of the transmitters, of the slide or caliper type for example.

The transmitter can consist of a blade, a profile or even a rod. Thus, it may be advantageous to construct a profile (with an evolving section), the central part of which comprises a section in the form of an inverted U to increase its buckling resistance and the ends of which are flat to facilitate its attachment to the ski.

The constituent material of the transmitter can be chosen from plastics, composite materials and metals, for example.

Each transmitter is arranged in the direction of the longitudinal axis of the ski. The end (60, 70) of each transmitter located on the side towards the contact lines (20, 21) is rigidly fixed to the beam by a complete connection (8).

By complete connection is meant a connection which does not allow any degree of freedom of the end (60, 70) relative to the beam. It can be a connection by screws, by gluing or even by welding. When the materials forming the top of the beam and those forming the transmitters are compatible with each other, it is preferable to bond the transmitter to the beam by the vibration welding process.

The other end (61, 71) of each transmitter is connected to the beam by a partial connection, free in translation in the longitudinal direction (I, I ') of the ski. By partial link is meant a link which allows at least one degree of freedom. In the case of the present invention, the choice of the direction of this degree of freedom is that of the direction along the axis (I, I ').

Each partial connection means consists of an interface layer (90, 91) of elastic or viscoelastic material connecting the underside of the end (61, 71) of each transmitter above the beam of the ski.

The hardness of an elastic material used can vary from 10 to 85 shore A. For a viscoelastic material, the hardness varies from 50 to 95 shore A for a modulus of elasticity between 15 and 160 MPa and a damping value of 0 , 13-0.72. Of course, these data are only exemplary embodiments for a temperature of 20 degrees Celsius and a frequency of 15 Hertz.

The material constituting the interface is chosen from rubbers and thermoplastic elastomers.

The interface is fixed on the transmitter and the top of the beam is made either by a thermosetting resin of the epoxy, polyester, vinylester or polyurethane type, or by a thermoplastic film or by any other means.

Each transmitter (6, 7) therefore comprises a free part (62, 72) between their linked ends (60, 61, 70, 71). In the context of the invention, the length (l _T1) of the free part of the front transmitter (6) is greater than the length (l _T2) of the free part of the rear transmitter; the ratio (l _T1 / l _T2) being more precisely between 1.5 and 2.5.

est, quant à lui, compris entre 0,15 et 0,25.In addition, the report ${\text{(l}}_{\text{T1}}{\text{+ l}}_{\text{T2)}}\text{/ LC}$

is, for its part, between 0.15 and 0.25.

est caractéristique de l'efficacité avant/arrière du dispositif.The ratio (l _T1 / l _T2) is characteristic of the balance of the front / rear behavior of the ski while driving. The report ${\text{(l}}_{\text{T1}}{\text{+ l}}_{\text{T2)}}\text{/ LC}$

is characteristic of the front / rear efficiency of the device.

est compris entre 0,2 et 0,25.Preferably, for a "Giant" type ski the ratio (l _T1 / l _T2) is between 2.2 and 2.5 and ${\text{(l}}_{\text{T1}}{\text{+ l}}_{\text{T2)}}\text{/ LC}$

is between 0.2 and 0.25.

Preferably, for a "Slalom" type ski (l _T1 / l _T2) is between 1.5 and 1.75, and ${\text{(l}}_{\text{T1}}{\text{+ l}}_{\text{T2)}}\text{/ LC}$ is between 0.15 and 0.2.

Advantageously, the fixed end (60, 70) of each transmitter must be located near its respective contact line (20, 21); at a certain distance (d1, d2) from it, however.

More specifically, the distance d1 separating the front end (60) of the front transmitter (6) from the front contact line (20) must be between 0.18 LC and 0.25 LC. The distance d2 separating the rear end (70) from the rear contact line (21) must be between 0.16 LC and 0.21 LC. Failure to respect these ranges results in unsatisfactory behavior of the ski which results in a tendency to understeer (in the sense that it is necessary to exert a greater effort to shorten the radius of curvature when cornering), when d1 and d2 are lower than the characterized ranges, and a tendency to lose stability and precision of the ends (tip / heel), when d1 and d2 are greater than the characterized ranges; any other parameter of the ski being identical elsewhere.

Preferably, for a "Giant" type ski, d1 must be between 0.18 and 0.2 and for a "Slalom" type ski, d1 must be between 0.2 and 0.25 (the influence of d2 is less sensitive on the behavior of the ski according to the type).

As illustrated in Figure 2; d1 is more precisely the distance between the front contact line (20) and the line separating the fixed end (8) from the free part (62). Likewise for d2; this is the distance between the rear contact line (21) and the line separating the fixed end (8) from the free part (72).

Figures 3, 3a and 3b schematically represent the operation of the invention. FIG. 3 shows the ski during bending, when a force F is applied to the center of the beam. In dynamic behavior, it is understood that a similar symmetrical stress is not the only one encountered. More generally, the front and rear parts of the ski are stressed differently at different times. The test in FIG. 3 is carried out according to the procedure for determining the overall stiffness in flexion of a ski according to ISO standard 5902. The point of application of the flexural force (F) is in the middle of LC. During bending, it can be seen that there is relative movement towards the rear of the rear end (61) of the front transmitter (6) and simultaneously, movement towards the front of the front end (71) of the rear transmitter (7). According to the schematic representation (fig. 3, 3a, 3b), the movable ends (61, 71) have moved, respectively, by Δ1 and Δ2, and these displacements have been braked due to the shearing caused by the interface layers ( 90, 91).

In the context of the bending test illustrated, Δ1 is always greater than Δ2 and the ratio Δ1 / Δ2 must advantageously be between 1.2 and 2.5.

est donnée à la figure 4. K représente en tout point la valeur tangente à la courbe.Depending on the nature of the elastic or viscoelastic element used, a variable stiffness K1 and K2 can be defined for each, equal respectively to the ratio F1 / Δ1 and F2 / Δ2 for a displacement speed of 20 mm / min and at a temperature 20 ° Celsius. Generally, for a viscoelastic material, the shape of the curve $\text{F = f (Δ)}$

is given in Figure 4. K represents at all points the value tangent to the curve.

Within the framework of the test of FIG. 3 respecting the operating mode of standard ISO 5902, the ratio K1 / K2 must be between 1.2 and 5. This ratio is characteristic of the efficiency of the treatment of the energy transmitted by the transmitter. In other words, comparatively, it is planned to dissipate or restore more at the front than at the rear of the ski due to the fact that the energy transmitted by the front transmitter is greater than that transmitted by the rear transmitter.

The invention is not limited to the mode illustrated in FIGS. 1 to 3 and which relates to an example using an elastic or viscoelastic element in the form of an interface layer working in shear.

It is also possible to provide for the partial connection means to consist of an assembly as illustrated in FIGS. 5 to 8.

In FIG. 6, the end (61) of the transmitter (6) is covered with a protective element constituting a cover (900) to allow the surface of the interface layer working in shearing to be increased. Thus, the upper surface of the end (61) of the transmitter is connected to the internal surface of the cover (900) by a second interface layer (90). The front opening (902) of the element (900) allows passage and participates in guiding the transmitter. The edges of the cover (900) are fixedly linked above the beam (1) by any means, such as screwing, welding, gluing, etc. An identical system is fitted to the rear transmitter (7).

Figures 7 and 8 illustrate more particularly compressible assemblies acting as partial connection means.

In Figure 7, for example, the end (61) of the transmitter (6) acts on an elastic buffer (901) or viscoelastic which is compressed against the transverse wall of the protective element (900) acting as a stop.

In the example of FIG. 8, the elastic element is constituted by a spring (903) which replaces the elastic buffer (901) of the example in FIG. 6.

Of course, the invention is not limited to the embodiments described and shown by way of examples, but it also includes all the technical equivalents and their combinations. This applies, in particular, to the equivalents likely to be able to replace the connecting means of the transmitter. Indeed, one could also provide a partial connection means constituted by an assembly comprising a spring or an elastic buffer connected to the beam and to the end of the transmitter so that it can be stressed under tension, without however depart from the scope of the invention. Likewise, the partial connection means could be a hydraulic damper consisting of a sealed chamber connected to the beam and containing a viscous fluid. Finally, provision could also be made for the provision of partial connection means in series (viscous / elastic) for example.

As an example, the dimensional characteristics by type of ski are gathered in the following table: CHARACTERISTICS -> TYPE LC (mm) l _T1 (mm) l _T2 (mm) d1 (mm) d2 (mm) l _T1 / l _T2 l _T1 + l _T2 LC d1 LC d2 LC GIANT Large size (GT) 1805 302 132 358.5 368.5 2.29 0.24 0.2 0.2 Small size (PT) 1555 222 92 301.5 295.5 2.41 0.2 0.19 0.19 INTERMEDIATE GT 1775 262 132 382 355 1.98 0.22 0.22 0.2 PT 1525 182 92 325 282 1.98 0.18 0.21 0.19 SLALOM GT 1755 222 132 411 346 1.68 0.2 0.23 0.2 PT 1505 142 92 354 273 1.54 0.15 0.24 0.18

Claims (11)

Ski consisting of an elongated beam (1) having a curved central part (2) of length (LC) between a front contact line (20) and a rear contact line (21); a raised front part (3) in tip and a less raised rear part (4) in heel; said central part (2) comprising an area for mounting the fasteners (5) corresponding to the standardized area,
characterized in that it comprises two transmitters (6, 7) arranged in said central part (2) and each on either side of said area for mounting the fasteners (5); one of the ends (60, 70) of each transmitter being connected to the beam by a complete link (8); the other end (61, 71) of each transmitter being connected to the beam by a partial connection means, free in translation in a longitudinal direction composed of an elastic and / or viscous element (90, 91) which is opposed the longitudinal displacement of said transmitter; the part (62, 72) of length (l _T1, l _T2) of each transmitter between the two connections being left free in translation at least, relative to the beam; the ratio of the free length (l _T1) of the front transmitter (6) to the free length (l _T2) of the rear transmitter (7) being between 1.5 and 2.5, and the ratio (l _T1 + l _{T2 )} on LC being, for its part, between 0.15 and 0.25. Ski according to claim 1, characterized in that the end (60, 70) of each transmitter, which is connected by a complete link, is situated on the side in the direction of the front (20) or rear (21) part; the other end (61, 71) being located on the side towards the mounting area (5). Ski according to claim 2, characterized in that the distance (d1) separating the front end (60) of the front transmitter (6) from the front contact line (20) is between 0.18 LC and 0.25 LC . Ski according to claim 2 or 3, characterized in that the distance (d2) separating the rear end (70) of the rear transmitter (7) from the rear contact line (21) is between 0.16 LC and 0 , 21 LC. Ski according to any one of the preceding claims, characterized in that, under bending stress, the displacement (Δ1) of the rear end (61) of the front transmitter (6) relative to the beam (1) is greater than displacement (Δ2) of the front end (71) of the rear transmitter (7); so that the ratio (Δ1 / Δ2) is between 1.2 and 2.5. Ski according to claim 5, characterized in that the stiffness (K1) of the elastic and / or viscous means (90) of the front transmitter (6) is greater than the stiffness (K2) of the elastic and / or viscous means (91) the rear transmitter (7); so that the ratio (K1 / K2) is between 1.2 and 5. Ski according to any one of the preceding claims, characterized in that the partial connection means (90, 91) consists of an interface layer of elastic or viscoelastic material connecting, at least, the lower face of the end (61, 71) of each transmitter (6, 7) above the beam (1) in order to work in shearing by the longitudinal displacement of said end (60, 70) relative to the beam. Ski according to any one of claims 1 to 6, characterized in that the partial connection means (90, 91) consists of a spring / stop assembly (903, 900) connected to the beam and working on compression. Ski according to any one of claims 1 to 6, characterized in that the partial connection means (90, 91) consists of an elastic buffer / stop assembly (901, 900) connected to the beam and working on compression . Ski according to any one of claims 1 to 6, characterized in that the partial connection means (90, 91) consists of a spring or elastic buffer assembly working in traction and connected to the beam. Ski according to any one of claims 1 to 6, characterized in that the partial connection means (90, 91) is a hydraulic shock absorber consisting of a sealed chamber connected to the beam and containing a viscous fluid.

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