IE61067B1 - Shoe bottom for sports shoes - Google Patents

Abstract

1. A shoe bottom, in particular for sports shoes, which in the shank (5) has weak locations (6, 7) for reducing the torsional stiffness about an axis extending substantially in the longitudinal direction of the shoe, in order to permit twisting, which is adapted to the natural movement of the foot, of the front sole portion (3) relative to the rear sole portion (4), about said axis, characterised in that the shank (5) of the shoe bottom (1, 2) is stiffened against bending about an axis extending transversely with respect to the longitudinal direction of the shoe by a striplike or rod-like stiffening element (9) which is directed in the longitudinal direction of the shoe.

Description

The invention relates to a shoe bottom, in particular for sports shoes · It is known from biomechanics that, in the natural rolling movement of the foot, between the front part of the foot and the heel, approximately in the region of the cuneiform bones, that is to say over the shank of the shoe bottom, there is a twisting action about an axis which extends substantially in the longitudinal direction of the foot. In order to take account of that twisting movement, it is known to provide the shank of the shoe bottom intentionally with weakened locations which permit the front sole portion to twist relative to the rear sole portion about an axis extending substantially in the longitudinal direction of the shoe (German patent specification No 804 901). Such weak locations are produced by reducing the thickness of the sole or the shoe bottom in the region of the shank thereof, while desirably there still remains a central limb portion extending substantially in the longitudinal direction of the shoe (see German published specification (DE-AS) No 14 85 804), or it is possible to provide recesses which extend inwardly from the side edge of the shoe bottom and which are filled by means of a filling material which is less stiff (German patent specification No 943 996).

The weak locations for reducing torsional stiffness in the shank of the shoe bottom necessarily also result in a reduction in the resistance to bending of the shoe bottom about a transversely a? extending axis. That is also desirable, in accordance with the above-indicated teaching, in which connection it was only proposed ( that a wedge-like lengthwise sole should be provided to prevent the shoe bottom from wearing out in the shank region of shoes with a heel member (see German utility model No 17 19 678), insofar as that design also provide! the foot with a firm support surface in the shank region. Particularly in the case of sports shoes however it has been found that the twistability or torsional mobility, which is desired in principle, in respect of the front sole portion relative to the rear sole portion, results in inadequate guiding and holding of the foot if the shoe bottom is not only yielding in respect of torsion in the shank region but is also readily bendable in that region, because as a result the foot has an excessive freedom of movement in the region of the metatarsus joints. That makes itself noticeable as a lack of lateral stability particularly when the foot of the runner encounters surface irregularities, which is generally inevitable when rambling or hiking, when running through woods, when jogging and the like.

The invention is therefore based on the problem of providing a shoe bottom of the kind set forth in the opening part of this specification, which ensures that the foot is better guided and held, without adversely affecting the desired torsional decoupling as between the front sole portion and the rear sole portion.

According to the invention there is provided a shoe bottom, in particular for sports shoes, which in the shank has weak locations for reducing the torsional stiffness about an axis extending substantially in the longitudinal direction of the shoe, in order to permit twisting, which is adapted to the natural movement of the foot, of tlie front sole portion relative to the rear sole portion, about '' said axis, characterised in that the shank of the shoe bottom is stiffened against bending about an axis extending transversely with respect to the longitudinal direction of the shoe by a strip-like or red-like stiffening element which is directed in the longitudinal direction of the shoe.

In accordance with ttie invention therefore the shank of the shoe bottom is stiffened against bending about an axis extending transversely with respect to the longitudinal direction of the shoe, } by stiffening means, in which connection the increased resistance to 5 bending is concerned in particular with a bending movement which occurs as a curvature of the shoe bottom in a convex configuration in a downward direction, that is to say, towards the groundengaging side of the shoe bottom.

It is particularly advantageous for the stiffening means ].O to be an element which is resistant to tension and which, extending in the longitudinal direction of the shoe, is anchored in the shoe bottom adjacent the ground-engaging side thereof. That element does not need to have any resistance to bending of its own, as the stiffening effect in respect of the shoe bottom is provided by virtue of the non-stretchability or the only very low degree of stretchability of the tension-resistant element and the arrangement thereof beneath the neutral bending fibre of the shoe bottom.

That has the significant advantage that the element which is resistant to tension and which is for example of a strip-like configuration does not have any torsional stiffness of its own and therefore does not in any way adversely affect the desired twistability of the front sole portion relative to the rear sole portion. Therefore the resistance to bending of the shoe hot tan in the shank t region may be controlled within wide limits by using such a tension25 resistant member, without thereby affecting the torsional stiffness of the shoe bottom in the shank. Another important advantage is that, in comparison with stiffening means which have their own resistance to bending (for example steel shank springs or the like), the stiffening effect by means of the tension-resistant means can be kept substantially lighter, which is an important consideration in relation to sports shoes. For, there are available materials which n‘ are resistant to tension and which are almost non-stretchable, with a high level of strength and of very low weight, for example metal wires, carbon and glass fibres, plastics wires and strip-like elements which are made from such materials.

E* «J In a particular embodiment of the invention, it is provided in known manner that the weak locations for reducing the torsional stiffness in the shank of the shoe bottom are recesses which extend ( F' inwardly from the edge transversely or inclinedly (being inclined forwardly or rearwardly) and which extend as far as a limb portion of the shoe bottom, which extends in the longitudinal direction of the shoe. The limb portion advantageously extends substantially centrally between the side edges of the shoe bottom. That configuration provides that the element which is strong in respect of tension extends along that limb portion. In that arrangement, with the usual production of the shoe bottom frcm plastics material, the tension-resistant element may be embedded in the limb portion adjacent to the underside thereof. It is also possible however for the element to be arranged along the free underneath surface of the limb portion, in which case a wearing sole which is fixed to the front sole portion and the rear sole portion ensures that the tension-resistant element does not cane directly into contact with the ground. In that way the tension-resistant element is arranged very close to the ground-engaging side of the shoe bottom.

Even if the stiffening means is formed by the abovementioned tension-resistant element, it can be embedded over its entire length in the shoe bottom so that it is capable over its entire length of transmitting forces with a stiffening effect. That is not necessarily the case however as, both in regard to stiffening means which are resistant to bending and also stiffening means which are only resistant to tension, the important consideration is essentially that the two ends thereof are adequately firmly fixed in the shoe bottom. For that purpose, anchoring inserts are desirably provided at the ends of the stiffening means, the anchoring inserts being fixed in the shoe bottom, for example by being directly embedded therein. The anchoring inserts are of such a / configuration that they can resist displacement in the longitudinal direction of the shoe, corresponding to the forces acting thereon when the shoe bottom performs a rolling movement.

An embodiment of the present invention is described in 5 greater detail hereinafter with reference to the accompanying drawings in which: Figure 1 is a partly broken-away view from below of an outsole according to the invention, Figure 2 is a side view of the outsole shown in Figure 1 partly in section taken along line II-II in Figure 1, and Figure 3 is a side view of part of the outsole shown in Figure 1, viewing in the direction indicated by the arrow III.

The outsole shown in the drawings which, together with an insole (not shown), forms a shoe bottom, essentially comprises an intermediate sole 1 of foamed plastics material, for example polyurethane, and a wearing sole 2 which is arranged at the groundengaging side and which may be of a profiled configuration. The outsole is subdivided into a front sole portion 3 and a rear sole portion 4 in the shank 5. The sole is subdivided by two recesses 6 and 7 which extend inwardly from the outer and inner edges respectively of the sole, being inclined forwardly and inwardly. As can be seen frctn Figure 3, the recesses 6 and 7 extend through the shoe bottom by more than half the height thereof. Between the mutually facing ends of the recesses 6 and 7, the intermediate sole 1 is unaltered in respect of its thickness, thereby providing a limb portion 8 which extends substantially centrally in the longitudinal direction of the sole. Due to the recesses 6 and 7, the front sole region 3 is ’’decoupled in respect of torsion, relative to the rear sole portion 4, in other words, the front sole portion 3 can twist relative to the rear sole portion 4 about an axis which extends substantially lengthwise of the limb portion 8; that corresponds to the natural movement of the foot when the foot performs a rolling motion, and therefore assists with the rolling ζ, motion.

Embedded into the intermediate sole 1 is a stiffening element which is generally indicated by reference numeral 9. The stiffening element 9 comprises plastics wires 91 which are strong in respect of tension and which are low-stretch (for example consisting of nylon) and which are combined in parallel side-byside relationship to form a flat strip, and anchoring inserts 92 and 93 which are fixed to the ends of the wires 91. The plastics wires 91 which are for example 1.5 mm in diameter are fixedly connected to the anchoring inserts 92 and 93 which are also advantageously made from plastics material, for example by being directly embedded into the anchoring inserts. The plastics wires 91 may also be joined together over their length. The anchoring inserts and 93 are of a plate-like configuration (see Figure 2) and have lateral leg portions 94. Provided in the anchoring inserts 92 and are openings 95 through which the material of the intermediate sole 1 can pass in the moulding or shaping operation, and thus embed the anchoring inserts in the sole.

As can be seen frcm Figure 2, the underside of the limb portion 8 along which the plastics wires 91 extend is disposed above the ground-engaging side of the wearing sole 2„ In the illustrated embodiment, the wearing sole 2 has an interruption or aperture 10 in which the plastics wires 91 are exposed, in both portions of the sole, namely in the front sole portion 3 and in the rear sole portion 4. That ensures that the strip formed by the plastics wires 91 is not prevented from assuming a curved configuration, in the f event of a torsional movement of the front sole portion 3 relative t V to the rear sole portion 4. The aperture 10 is not necessary however; it is entirely possible for the stiffening element 9 and in particular the plastics wires 91 to be completely covered by the wearing sole 2, in order to protect the wires 91 iron damage.

It will be seen from the foregoing description that the resistance to bending of the outsole about a transverse axis extending perpendicularly to the limb portion 8 can be controlled by the resistance to tensile stretching of the stiffening element 9.

If the resistance to bending of the sole is to be increased, it is possible to envisage increasing the number of plastics wires 91 and therewith the width of the strip formed thereby. In principle it is also possible to envisage increasing the thickness of the plastics wires, but care should be taken to avoid increasing the torsional stiffness of the shoe bottom in the shank region thereof, by an increase in the thickness of the wires.

It will be appreciated that, instead of the plastics wires 91 described in the illustrated embodiment, it is also possible to use other stiffening means which are resistant to tension. Thus, it is possible to envisage providing, by means of the anchoring inserts 92 and 93, a mesh, netting or cloth of glass or carbon fibres, which is of a strip-like configuration and which is embedded in the sole in a similar manner to that described above. By choosing the width of the strip formed by such a cloth, it is possible to control within wide limits the tensile strength and thus the resulting bending strength, without noticeably affecting the weight of the shoe bottom. However, also included within the scope of the invention is the arrangement of flat metal strips which, by virtue of being small in thickness, have a correspondingly low level of bending strength while however having considerable tensile strength.

Claims (9)

1. A shoe bottom, in particular for sports shoes, which in shank has weak locations for reducing the torsional stiffness about an axis extending substantially in the longitudinal 5 direction of the shoe, in order to permit twisting, which is adapted to the natural movement of the foot, of the front sole portion relative to the rear sole portion, about said axis characterised in that the shank of the shoe bottom is stiffened against bending about an axis extending transversely with respect to 10 the longitudinal direction of the shoe by a strip-like or rcd-likee stiffening element which is directed in the longitudinal direction of the shoe.

2. A shoe bottom according to claim 1 characterised in that the stiffening element which is strong in respect 15 of tension and which extends in the longitudinal direction of the shoe is anchored in the shoe bottom adjacent to the groundengaging side thereof.

3. A shoe bottom according to claim 2 characterised in that the element which is strong' in respect of tension is of a strip20 like configuration and is fixed in the shoe bottom at the ends of the element by means of anchoring inserts.

4. ,, A shoe bottom according to claim 2 or claim 3 wherein the weak locations for reducing torsional stiffness are recesses which extend inwardly from the edge transversely or inclinedly and which extend to a limb portion of the shoe bottom, which extends in the longitudinal direction of the shoe, characterised in that the element which is strong in respect of tension extends along the limb portion„

5. A shoe bottom according to claim 4 characterised in that said element which is strong tn respect of tension extends along the free underneath surface of the limb portion.

6. A shoe bottom according to one of claims 2 to 5 characterised in that the element which is strong in respect of tension is formed by rods or wires of metal, plastics material, carbon or glass fibre or the like.

7. A shoe bottom according to claim 6 characterised in that the rods or wires are arranged in parallel relationship with each other and are connected to each other for example by adhesive or welding.

8. A shoe bottom according to one of claims 2 to 5 characterised in that the element which is strong in respect of tension is a cloth or mesh consisting of low-stretch fibres which are resistant to tensile force.

9. A shoe bottom, in particular for sports shoes, substantially as herein described with reference to the accompanying drawings.