FR2971675A1 - FLEXIBLE SHOE SHELL AT THE METATARSO-PHALANGIAN JOINT - Google Patents

Abstract

This hull is more particularly intended for mountain or mountain ski cross-country ski boots. The difficulty is to achieve a comfortable shell, light and rigid in torsion while having flexibility in flexion at the metatarsophalangeal joint. The boot according to the invention has a shell (1) composed of two cradles (2), (3) and a flexion zone (4). The cradle construction provides good rigidity to the hull in these areas. The walls of the cradles will be fine to ensure a certain comfort and good tightening and the bending zone (4) will be thin and devoid of vertical parts to allow flexion. This bending zone (4) can be stiffened using a blade (9) which in a first configuration does not contribute or little to the rigidity of the shoe and in a second configuration when it is attached to the using the lever (10) at the rear part of the shoe helps to stiffen the shoe.

Description

The invention relates to a shoe more particularly intended for the practice of cross-country skiing, mountain skiing or mountaineering The practice of these disciplines requires the use of relatively rigid shoes in torsion between the front and the back of the shoe while retaining the flexural flexibility required to unwind the foot at the metatarsal joint. This rigidity, which was lacking on the first cross-country ski boots at the time of the appearance of the so-called "skating footstep" technique, found a technical answer with the use of reinforcements generally made of composite materials which are superimposed and connected to the existing structure which is made of thermoplastic materials. The shoes are now stiffer, allowing better control of skiing and balance but they have also become heavier, since the reinforcements come in addition to an already existing shell.

The shoe according to the invention overcomes this drawback since there is no more plastic shell superimposed on composite reinforcements but a single shell preferably made of composite material which has both the properties of torsional rigidity and flexural flexibility required for practice with a greatly reduced weight.

Thus, for example, the cross-country ski boots of the trade for the practice of the skater's step weigh about 700gr per foot while the shoe made with a hull according to the present invention weighs about 300gr. The difficulty is to reconcile sufficient rigidity without sacrificing comfort. This requires a fair use of the composite materials and more particularly by the choice of thicknesses and geometry of the shell. The hull has two cradles forward and back of the bending zone. This cradle-shaped construction imparts high rigidity to the hull in these areas. These cradles will be very thin on the side walls to ensure a certain flexibility useful for comfort and tightness and not to weigh down the hull. For example, the thickness of the shell must be less than 1.5 mm in the lateral parts in order to achieve this objective. Between the two cradles and in order not to excessively soften the hull, the bending zone is thicker than the rest of the hull and may include cross-fibers diagonally to the longitudinal axis, this reinforcing the torsional rigidity. The thickness of this bending zone should be less than 4 mm in order to achieve this objective. Part of the fibers in this zone will be oriented between 40 ° and 70 ° on the one hand and between -40 ° and -70 ° on the other hand with respect to a longitudinal axis of the shell, which has the effect of giving good rigidity in torsion without blocking the flexion. This bending zone will not have side walls that would be incompatible with flexibility and sufficient strength. In addition, the flexural stiffness of the ski cross-country skiing or mountaineering shoe is more or less important and sometimes necessary. Today there is no answer to this constraint and the only solution is to have several shoes according to practice. Take the case of cross-country skiing requires a pair of soft flexural shoe for the practice of the so-called classical technique, and a pair of rigid flexural shoe for the practice of the technique of the skating step. This can be particularly tricky in the case of competitions where there is a combination of two events, a classics event followed immediately by a skater's step without a stopwatch. The shoes used for this type of event are mixed shoes whose rigidity is intermediate between the two types of shoes. It is therefore a compromise not ideal in each of the techniques.

The shoe according to the invention overcomes this disadvantage by proposing an adjustable stiffness depending on the type of practice. Thus, the same shoe can be flexible in one flexion and rigid in flexion in another simply by activating a connection between the shell and an auxiliary blade. The shell therefore comprises a blade superimposed on the sole and secured to it in front of the flexion zone but independent of it beneath the flexion zone and behind it. The first function of this blade is to stiffen the hull in "reverse" flexion that is to say when the foot goes back and the front of the shoe is maintained on the ski for example. This is particularly useful for a mountain ski boot that will tend to bend upside down when pressing on the upper part of the shoe. The shoe without this blade could then break simply on a back support. The second function of this blade is to stiffen the hull flexion when it is coupled to the hull. One thus obtains with the same shell, a soft shoe in one case and rigid in the other.

In order not to unnecessarily burden the hull, only certain areas of contact preferred will be provided with rubber to protect the hull and to allow walking safely. These zones are defined as follows: The heel and the front part of the hull which are the contact zones at the beginning and at the end of the pitch, the lateral surfaces of the flexion zone as well as the central part of the zone of bending privileged point of support for the standing station or during the unfolding of the foot. BRIEF DESCRIPTION OF THE FIGURES Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of nonlimiting examples, and represented in the accompanying drawings, in which: FIG. a side view of a shoe according to a preferred embodiment of the invention; FIG. 2 represents a section at the level of the bending zone of said shoe. FIG. 3 represents a view from above of the shell of the boot according to the invention, where the fibers oriented at 60 ° and the diagrams are shown schematically. 60 ° with respect to the longitudinal axis FIG. 4 represents a profile view in section along the longitudinal median plane of the boot provided with an auxiliary blade. Figure 5 shows a bottom view of the same shoe with the lever 5 in the open position Figure 6 is a sectional view along the longitudinal median plane of a mountain ski boot provided with a collar at the top. FIG. 7 shows a profile view in section along the longitudinal median plane of the boot when it is in flexion is that the blade is free. FIG. 8 is a profile view in section along the longitudinal median plane of the shell. bending when the blade is coupled to the portion of the hull behind the bending zone using the locking lever FIG. 9 is a bottom perspective view of the hull provided with localized gum area.

With reference to FIGS. 1 and 2, the shell (1) has two cradles (2) and (3) and has a bending zone (4) devoid of lateral flanks and of reduced thickness to allow bending of the foot of the user. Figure 2 shows a section of the bending zone which should be thin to allow bending. The lines (5) are parallel and spaced less than 4 mm in order to achieve this objective with composite materials composed of carbon fiber or fiberglass. FIG. 3 shows the arrangement of the fibers (6), (7) of the shell in the bending zone which are crossed and form an angle of about 60 ° and -60 ° with the longitudinal axis (8) in order to ensure a continuity of torsional rigidity of the hull 25 in this area weakened by the absence of lateral lifts. In Figure 4 we see an alternative construction of the hull which has an auxiliary blade (9) superimposed on the sole. This blade (9) is integral with the shell 4 (1) in the forward portion of the bending zone (4) and is detached from the shell in the bending zone and behind it. In Figure 5 can be seen from below the shell and the auxiliary blade (9) and the locking lever (10) in a position where the blade is free relative to the shell. The arrow (11) indicates the rotational movement of the lever which makes the blade (9) integral with the shell (1). In FIG. 6, the shell according to the invention can be seen provided with a collar (12) for the practice of alpine skiing. When the user leans back, he exerts a force (13) on the collar (12) which has the effect of folding the shoe upside down in the direction (14). The auxiliary blade (9) serves to prevent this reverse bending of the hull. In Figure 7 the hull is bent and the blade (9) remains in place, the blade does not help to stiffen the hull in this case. In FIG. 8 the hull (1) is bent as is the auxiliary blade (9) which in this case is secured to the hull by means of the lever (10). In this case the hull is more rigid. In Figure 9 we can see the location of the zones of gums. The zone (15) is the zone of the heel, the zones (16) and (17) are arranged at the level of the bending zone where the shell is the widest, in the middle of these there is the zone ( 18) which is a preferred area of contact with a gliding apparatus, and the area (19) in front of the shoe is the last contact zone before the foot leaves the ground.

Claims (6)

REVENDICATIONS1. Shoe shell (1) consisting of two cradles (2) and (3) and a flexion zone (4) at the metatarsal joint, characterized in that the lateral parts of the cradles have a thickness of less than 1.5 mm and that the hull in the bending zone to a section that is inside two parallel lines distant less than 4 mm 2. Shoe shell according to claim 1 characterized in that it is made of composite materials with reinforcements of the carbon fiber type, fiberglass or aramid 3. Shoe shell according to claims 1 and 2 characterized in that the flexion zone (4) comprises fibers (6) oriented between + 40 ° and + 70 ° on the one hand and other fibers (7) oriented between -40 ° and -70 ° on the other hand with respect to the longitudinal axis (8) of the shoe 4. Shoe shell (1) according to claim 1 provided with a flexion zone (4) at the articulation of the metatarsals characterized in that it has a blade (9) disposed under the sole, integral with the hull in the forward part of the bending zone (4) and independent of the hull in the bending zone. 5. Shoe shell according to claims 1 to 4, characterized in that a lever (10) is used to secure a blade (9) to the hull behind the bending zone (4) shoe. 6. Shoe having a shell according to your preceding claims characterized in that it has only a few localized zones provided with rubber defined as follows: the lateral edges of the flexion zone (16) and 25 (17), the central part of the bending zone (18), the heel (15) and the front part of the sole (19)