DEVICE FOR ANCHORING A BINDING TO A DOWNHILL SKI

The present invention relates to a device for anchoring a binding to a downhill ski.

The technique of downhill skiing has become highly developed in recent years by virtue of the interposing of a rigid metal plate between the toe and the heel fixing unit of the ski boot binding. This plate is used mainly to :

- interpose a rise in order to improve ski manoeuvrability on a counterflex, by enabling it to reliably perform lateral angulation without the boot coming into contact with the snow,

- damp vibrations during the descent,

- improve distribution of the load applied by the boot (sum of the skier's weight and the centrifugal force applied to its centre of mass) so that it does not become transmitted to the ski in a concentrated rather than uniformly distributed manner. In reality this load is divided into two substantially concentrated components located at the ends of the plate. In order to satisfy the functions discussed above, the plate must be as equally rigid as the boot sole. However the ski is also required to maintain its flexibility when secured to the plate, whereas if it were rigidly connected the resultant stiffness would be intolerable, hence it has been proposed that the holes for the screws for fixing the plate to the ski be made longitudinally slotted.

This solution substantially eliminates the drawback of longitudinal forces but certainly does not eliminate the forces perpendicular to the ski, which arise as a result of its counterflex, and cause the plate to lose

support continuity on the ski, which on counterflexing gives rise to an underlying empty space.

On the other hand, the solution of making the plate of flexible material so that it can deform to follow the ski deformation involves the drawback of a situation of paradoxical incongruence with respect to the boot, the sole of which must necessarily be rigid and hence induces a load concentration in two ski positions on the ski, corresponding to the binding components, this situation then repeating that of plateless skis.

Finally the solution of providing a plate divided into two portions (front below toe and rear below the heel fixing unit) in no way eliminates the drawback of concentrated forces as these are necessarily generated at these two plate portions.

An object of the invention is to eliminate these drawbacks by providing a rigid plate for ski bindings which provide uniformly distributed distribution of the resultant of the force load to which it is subjected.

This and other objects which will be apparent from the ensuing description are attained according to the invention by a device for anchoring a binding to a downhill ski as described in claim 1.

The present invention is described hereinafter wiin reference to the accompanying drawings, in which:

Figure 1 is a schematic section through an anchoring device according to the invention applied to a ski, Figure 2 shows it during ski counterflexing, Figures 3, 4, 5 and 6 show modified embodiments thereof. Figure 7 shows the distribution of the force F deriving from the load exerted on the plate by theskier,

Figures 8 and 9 show two diagrams of the stresses of a ski provided with a traditional plate and provided with an anchoring device according to the invention.

As can be seen from the figures, the anchoring device of the invention comprises a rigid plate 2 made preferably of metal or a carbon fibre reinforced composite material and connected to the ski 4 at a hinge 6 transverse to the ski axis and positioned substantially at the ski centre. At the ends of the plate 2, on hinges 8, two arms 10 are pivoted, each provided with a pin 12 inserted into a slotted hinge 14 fixed to the ski 4. On the pin 12 there acts a pre-tensioning device 16 rigid with an elastic bracket 18 fixed to the plate 2.

In a modified embodiment, not shown in the drawings, the plate and arms form a monolithic structure.

Said arms, which can possess flexibility in the vertical plane, can have a width equal to or less than that of the plate and can taper in the vertical or horizontal direction towards the ends.

Between the plate 2 and the ski 4, two elements 20 of precompressed elastic material of rubber type are inserted capable of transmitting the load to the ski in a uniformly distributed manner. In order to maintain a uniform load distribution along the plate, given that during counterflexing of the ski this forms with the plate a space which decreases from the centre towards the fixed end of the plate, said elements are preferably formed with a precompression which is differential in progressing from the region closest to the hinge towards the end, with the precompression load greatest in the region closest to the hinge.

- A -

Said element consists of a hydrostatic, oleostatic or pneumatic bearing, i.e. a hollow body filled with water, oil or air able to ensure a load distribution which is always homogeneous between the plate and ski independently of their distance apart. This bearing can be advantageously provided with a device for varying the pressure of the internal fluid.

The elastic element acting by compression can also consist of coil or cup springs of metal or stratified elastomeric materials, these also extending longitudinally with a degree of yielding which increases towards the ends of the plate.

In the embodiment shown in Figure 3 both ends of the plate are provided with a transverse horizontal hinge 24 for pivoting an arm 26, the ends of which are provided respectively with a pin 28 insertable into a slotted hinge 14 and with a height-adjustable counteracting member 30 interacting with an elastic member 32 provided on the upper surface of the plate 2.

In the embodiment shown in Figure 4 the plate is substantially similar to the preceding but is connected to the ski by an insertion joint.

In the embodiment shown in Figures 5 and 6 the plate is connected to the ski by a slider connection, one of the two arms 26 (the front arm) being connected to the ski on a hinge 38 while the rear arm is connected in the aforesaid manner.

This configuration enables the plate 2 to slide and modify the position of the ski boot toe during counterflex, enabling the skier to improve ski control and easiness of turning while maintaining optimum speed.

In the embodiment shown in Figure 7, the length of the front arm is greater than that of the rear arm in order to dispose the front slotted hinge connected to the ski in a position significantly advanced towards the shovel portion and the rear hinge in a position significantly withdrawn towards the tail portion. In this case the inequitableness of the action F exerted by the skier on the boot is converted immediately below the plate into the force Fc and into the distributed forces F'" of the elastic bearings, but even more widely apart into the forces Fant and Fpost outside the base plate, in the regions most adjacent to the shovel portion and to the tail portion.

Figures 8 and 9 show the distribution diagrams for a load of 800 Newton exerted by the skier on a ski positioned at an angle of 40° on a test machine.

From these diagrams it can be seen that a load exerted on a ski with a traditional plate (Figure 8) presents a discontinuous pattern with localized load peaks which give rise to greater friction in sliding along snow, and regions of virtually zero load, even in central ski positions, resulting in the generation of vibrations.

In contrast, the load diagram for a ski provided with the anchoring device according to the invention (Figure 9) shows a pattern without peaks and hence a more homogeneous force distribution.

From the aforegoing it is apparent that the anchoring device of the invention presents the advantage of transmitting the load in a uniformly distributed manner via the elastic elements, so preventing vibration of the ski or a high load therefrom acting on the snow's surface.