REINFORCING INTERFACING WITH A METATARSAL BENDING MECHANISM FOR A CROSS-COUNTRY SKI BOOT

The invention relates to a reinforcing interfacing for a sports shoe, particularly for but not limited to a cross-country ski boot, which reinforcing interfacing extends from the front portion to the heel portion of the shoe and consists of a sole surface member and a lateral structure extending therefrom, said lateral structure starting in the metatarsal region of the shoe and rising toward the ankle to a convenient height that ensures an optimal connection of the lower and upper lateral elements of the sports shoe. The reinforcing interfacing comprises a bending mechanism in the metatarsal region of the shoe, which provides flexibility in the said region as well as a larger contact area between the ski and the boot, while at the same time ensuring perfect torsional and lateral stability, thereby saving energy to the cross-country skier and allowing optimal leg thrust (i.e. push-off), gliding and, consequently, speed. The invention pertains to class A 61 F 5/00 according to the international patent classification.

The main technical problem overcome by the invention as claimed is that of achieving perfect torsional and longitudinal stability along the entire length of the shoe, while at the same time ensuring adequate bending in the region of the metatarsus. The invention disclosed herein also overcomes the technical problem of enabling automatic edging, i.e. tilting of the ski on its inner edge at

the moment the cross-country skier is passing from the gliding phase to the thrust phase. Another technical problem solved by the invention as claimed is that of ensuring an optimal contact area between the boot and the binding, thereby reducing losses in the transfer of the force to the ski, allowing the user to increase the thrust force and consequently to increase speed.

Known solutions in this field comprise an embodiment, wherein the sole of the shoe and the lateral structure are made as separate parts, known technological processes being employed to secure said lateral structure to the sole. Most sports footwear is produced this way, particularly footwear which in addition to rigid lower and potentially lateral components also comprises softer upper portions, such as cross-country ski boots. It is a disadvantage of this type of structure that it does not ensure stability and other features in a degree that could be compared to the design, wherein the lower and lateral structures are manufactured as one integral unit.

According to the patent document No US 005887361 , the rear portion of the lower and lateral structure is made of one piece, namely of the sole portion, rising toward the heel to form a lateral structure of convenient height. The proposed approach allows a better stabilization and positioning of the heel in particular. The solution disclosed in the said patent, however, is only concerned with structural designs for efficiently stabilizing the heel, whereas the front portion of the foot is left out, in that the lateral structure is not extended to the frontal region. In addition, the solution set forth in the said patent has no provisions for the bending of the sole in the metatarsal region, and thus does

not offer the advantage of a larger contact area between the boot and the binding.

A similar approach may be found in the patent document No US 6,524,266 B1 , which is limited, however, to the stabilization of the ankle only.

The patent document No WO2004/002255 discloses a solution for improving the bending of the sole along the entire length thereof by means of embedded elements of elastic material, situated on the external side of the sole. By ensuring flexibility along the entire length of the foot, however, the shoe loses the required torsional and longitudinal stability.

The patent document SI 20715 effectively improves the tilting of the ski on its inner edge in the thrust phase by means of a shifted gaiter. This is achieved in the thrust phase, with the disadvantage that, because of the permanently shifted gaiter, the ski is tilted on its inner edge in the gliding phase as well, so that gliding is less than optimal, slowing the skier down and causing the ski to be drawn outwards. Consequently, the cross-country skier must needlessly spend energy just to keep the ski aligned in the neutral position.

None of the solutions presented thus far enable efficient lateral and longitudinal stability of the shoe to be attained while allowing bending in the metatarsal region, and thus do not offer improved energy efficiency of the leg thrust and of the transfer of the forces to the ski, which would increase speed in cross-country skiing and reduce energy consumption at the same time.

The solution to the examined technical problem of achieving perfect lateral and longitudinal stability of a sports shoe while ensuring adequate bending in the metatarsal region thereof is provided by a particular structural arrangement,

composed of a reinforcing interfacing, extending on the lower side from the toe portion to the heel portion of the shoe, and of a lateral structure extending therefrom, said lateral structure starting in the metatarsal region of the foot and rising toward the heel to a convenient height which ensures an optimal interconnection of the lower and upper lateral elements of the sports shoe. The structural reinforcing interfacing of the invention is made of a material of convenient rigidity, which prevents bending, such as titanium and other materials with similar properties. To secure the reinforcing interfacing to the interior of the shoe a method is used which ensures a reliable connection of both elements of the sports shoe and comprises in the metatarsal region thereof a bending mechanism, consisting of pipes linked by a pin, which allows natural bending in the said region. An alternative arrangement of the bending mechanism consists of a pin and two connectable elements of the frontal portion and the main body of the inventive reinforcing interfacing. The bending mechanism allows interactive operation of the frontal portion of the reinforcing interfacing, extending from the toes to the metatarsus of the foot, and the second portion thereof, extending from the metatarsus to the heel.

Two alternative arrangements of the bending mechanism are envisioned, whereof the first is positioned at a right angle and the second is positioned at a non-right angle relative to the axis of symmetry of the sole. The first arrangement is adapted to the traditional cross-country skiing technique. In traditional cross-country skiing, the cross-country skier does not lean on the lateral edge of the ski when pushing off, so the bending mechanism must be arranged perpendicularly to the axis of the sole. The second arrangement is

designed to suit the skating technique of cross-country skiing. The skating technique requires the ski to react instantaneously, i.e. to tilt on its internal edge the very moment the heel of the shoe starts to rise, which is to say, when the skier is passing from the gliding phase to the thrust phase. The moment the heel is lifted, the non-perpendicular disposition of the bending mechanism relative to the axis of the sole enables the ski to be tilted on its inner edge, whereby optimal push-off without any unnecessary energy loss is achieved and, consequently, a solution is provided to the second technical problem.

In addition to ensuring adequate flexibility, the bending mechanism also solves the technical problem of providing an optimal contact area between the sole of the shoe and the binding. By ensuring adequate flexibility in the metatarsal region of the shoe, the contact area between the sole and the ski, generally very limited due to the binding at the toe tip, is increased. Because of the increased contact area, moreover, a stronger thrust may be achieved, increasing the skier's speed.

The invention shall hereinafter be described in more detail with reference to a preferred embodiment thereof and the accompanying drawings, representing:

Figure 1 axonometric view of the reinforcing interfacing of a cross-country ski boot with a metatarsal bending mechanism according to the invention;

Figure 2 longitudinal cross section of the reinforcing interfacing of a crosscountry ski boot with a metatarsal bending mechanism according to the invention;

Figure 3 top view of the reinforcing interfacing of a cross-country ski boot with a metatarsal bending mechanism according to the invention; Figure 4 top view of the reinforcing interfacing of a cross-country ski boot with a metatarsal bending mechanism according to the invention with an alternative arrangement of the bending mechanism having two connectable elements;

Figure 5 side view of a cross-country ski boot with a bending mechanism according to the invention, with the entire sole of the boot lying on the ski in a contiguous manner;

Figure 5a alternative configurations of the bending mechanism; Figure 6 side view of a cross-country ski boot with a bending mechanism according to the invention in the thrust phase;

Figure 7 top view of a cross-country ski boot with an arrangement of the bending mechanism suitable for the traditional technique, represented schematically;

Figure 8 top view of a cross-country ski boot with an arrangement of the bending mechanism suitable for the skating technique, represented schematically.

The reinforcing interfacing with a metatarsal bending mechanism for a crosscountry ski boot in accordance with the invention is embodied in a sports shoe, preferably in a cross-country ski boot 1 , and is composed of a sole surface 2 and a lateral structure 3, which together form the basic structure of the shoe. The lateral structure 3 extending therefrom starts in the metatarsal area of the shoe 1 and ends in the heel region at an adequate height.

The sole surface 2 essentially consists of two mutually movable parts, namely, the frontal portion 4 of the sole surface 2 and the main body 5 of the sole surface 2, connected to each other by means of the bending mechanism 6, which may be formed by both portions of the sole surface 2 in the shape of tubular elements 7, pivotably joined together by the pin 8, or, alternatively, the mobile connection between the frontal portion 4 and the main body 5 may be realized by means of connectable elements 9 in the form of wire strings.

In the gliding phase, the shoe 1 rests on the binding 10 and the ski 11 with the entire length of the sole surface 2. The elements of the bending mechanism 6 assume the neutral position.

The structural arrangement of the bending mechanism 6 according to the first embodiment, wherein the bending mechanism 6 is formed by both portions of the sole surface 2 in the shape of tubular elements 7, pivotably joined together by the pin 8, allows double or triple bends to be embodied (Figure 5a).

In the thrust phase, the heel portion 12 of the shoe 1 is lifted up, resulting in a bend being formed in the metatarsal region of the shoe 1. The elements of the bending mechanism 6 are shifted in the appropriate direction, whereby a larger contact area between the shoe 1 and the ski 11 is ensured, improving the energy efficiency in the thrust phase while maintaining a perfect torsional and longitudinal stability, as provided by the reinforcing interfacing of the invention.

The disposition of the bending mechanism 6 depends on the skiing technique employed. For the traditional cross-country skiing technique the bending mechanism is placed at an angle of 90° relative to the symmetry axis of the sole, whereas for the skating technique the said angle is between 80°

and 90°. The arrangement of the bending mechanism for the skating technique of cross-country skiing corresponds to a non-right angle relative to the axis of symmetry of the sole.

In addition, a conveniently shifted bending mechanism (between 60° and 90°) relative to the symmetry axis of the sole (Figure 8) also ensures that the ski will be automatically tilted on the edge.

The reinforced interfacing structured as per the invention provides perfect lateral and longitudinal stability to the sports shoe while allowing adequate bending in the metatarsal region thereof, whereas the bending mechanism enables interactive operation of the frontal portion of the reinforcing interfacing, extending from the toes to the metatarsus of the foot, and the second portion thereof, extending from the metatarsus to the heel.