Toe piece for alpine ski safety binding

Details Toe piece for alpine ski safety binding Toe piece for alpine ski safety binding

1996-09-24

1999-05-04

Mai, Lanna

Land vehicles

Skates

Shoe attaching means

280629, 280634, A63C 9085

Patent

active

058994840

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a toe piece for an alpine ski safety binding. On a ski, the purpose of such a toe piece is to hold the front end of a ski boot in place, while allowing this end to be released when the force exerted on the toe piece exceeds a predetermined value. This predetermined value is referred to as the triggering threshold. It is chosen in such a way that the force holding the boot is less than the force needed to break the bones or tear the ligaments of the skier wearing the ski.
The lateral force holding the boot is the force, perpendicular to the axis of the boot, exerted at the extreme front end of the boot and corresponding to the moment which the skier must exert in order to pivot it about an axis lying in proximity to his tibia.
On known ski binding toe pieces, the boot of the skier is held in a jaw having two lateral arms. Each lateral arm pivots about a vertical pin. It is returned into its neutral position by a spring. The boot can be released from the binding when the jaw pivots to a given angle about the pin, corresponding to a given elastic travel. The elastic travel is the distance covered by the front end of the boot before being released. A return force exerted by the spring corresponds to each angular position. This force is equal to the spring constant multiplied by the total compression or extension of the said spring.
During the lateral travel, the force holding the boot depends on the following five factors: rounded edges of the front of the boot, about the pivot axis (the tibia); presses the boot against the toe piece, reducing the holding force;
In general, the result is that the force holding the boot increases starting from the neutral position, reaching a maximum or triggering threshold after a part of the total travel. This part varies depending on the setting of the threshold.
The elastic travel is in fact composed of a first, useful part, in which the return force of the spring can actually overcome the frictional forces plus a component of the longitudinal thrust of the heel piece, and returns the boot to the neutral position, and of a second part, in which the resultant of these forces combined with the decreasing lever arm acting on the rounded tip of the front of the boot about the tibia no longer returns the boot, which therefore remains locked in an off-centred position, if no additional external force is exerted, either to release it or to recentre it.
The possibility of adjusting the triggering threshold on ski binding toe pieces is known. This threshold is not actually the same for all skiers. It varies depending on the skier's height and weight, as well as his proficiency.
It is possible to adjust the triggering threshold by varying the return force exerted by the spring. The solution adopted is generally that consisting in compressing or stretching the return spring to a varying degree when the jaw is in its neutral position. The more the spring is then compressed or stretched in this neutral position, the higher is the triggering threshold.
With such bindings, the force for returning the jaw to its neutral position, for positions before the release position is reached, depends on the setting of the triggering threshold. When the triggering threshold is set close to the minimum, the return spring is not greatly compressed in the neutral position. Because of this, close to this position, the holding force is small compared with the force of the triggering threshold. This force ratio is referred to by the term boot holding, and the result of this low degree of holding is a feeling of lack of firmness for the skier at the start of the elastic travel.
When the triggering threshold is set to an intermediate or maximum value, the return spring is prestressed to a much greater degree when the jaw is in the neutral position, and the holding-force close to this position is nearer to the force of the triggering threshold.
With such bindings it is also observed that, when the triggering threshold is set close to the minimum, the component of the axial force produ

REFERENCES:
patent: 4735434 (1988-04-01), Sedlmair
patent: 4779891 (1988-10-01), Freisinger et al.
patent: 4889359 (1989-12-01), Kowatsch et al.
patent: 4938497 (1990-07-01), Goud
patent: 5050902 (1991-09-01), Bougue et al.
patent: 5121939 (1992-06-01), Peyre

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