EP0320993A1 - Running sole for sports shoes - Google Patents

Abstract

PCT No. PCT/DE88/00767 Sec. 371 Date Aug. 9, 1989 Sec. 102(e) Date Aug. 9, 1989 PCT Filed Dec. 16, 1988 PCT Pub. No. WO89/05593 PCT Pub. Date Jun. 29, 1989.An outsole of flexible plastic material for sports shoes with a recess (4) beneath the heel support surface (A) for accommodating a plurality of individual bodies (5) comprising a resilient material, which fill the recess and which in the non-loaded condition bear against each other only in a region-wise or point-wise manner, forming spaces therebetween. The individual bodies (5) may be in the form of balls and may be joined together by a matrix of small connecting limb portions, to provide for better handling.

Description

The invention relates to an outsole made of resilient plastic for sports shoes with the features according to the preamble of claim 1.

The problem of designing the outsole of sports shoes in such a way that it adequately absorbs (dampens) the high loads on the musculoskeletal system of the runner, which occurs suddenly, and at the same time does not impair the natural running behavior, is the subject of numerous proposals and practical developments. The main load when touching down naturally takes place in the heel area, since at least the average runner puts the foot on there first, so that the heel and leg of the runner are loaded by a large force during a short period of time in the rolling phase. The magnitude of this force essentially depends on the "spring travel" of the outsole, the kinetic energy, which is mainly determined by the body weight and the running style of the runner, is absorbed relative to the track surface until the heel stops. A compromise has always been made in the design of the sole with regard to this spring travel, since a long travel which is desirable in itself because of the lower load gives the runner a feeling of swimming which affects the mileage and also promotes the risk of injury due to the uncertainty in the foot guidance. This compromise also takes into account the different body weights of the runners because, obviously, an outsole that provides sufficient travel for a heavy runner and thus sufficient cushioning is too hard for a light runner, while the outsole that is adapted to the light runner is compressed too much by the sole loads exerted by a heavy runner and therefore mentioned the above Creates or "punctures" swimming sensation. There are therefore numerous outsoles of the type mentioned at the outset which have interchangeably inserted support bodies or the like for the individual adaptation of the damping ability of the outsole to the different body weights of the runners in recesses under the heel contact surface (cf. DE-AS 29 04 540; DE-OS 32 45 964). However, these known solutions presuppose that the runner himself is able to determine the damping required for him, ie to make the selection of the damping bodies required for this himself, but this is by no means always the case.

It is also known that the spring elasticity of the sole materials of the known outsoles produces a so-called "catapult effect" by accelerating the foot upward with a force corresponding to its compression in the amount of local stress reduction during the rolling process. Although this catapult effect is considered to be conducive to mileage, it is disadvantageous to health in a pronounced form since the sole "strikes back" on the foot with the same force with which it was previously loaded when it was put on when the impressed load was returned fully elastic. This causes damage in particular in the area of the Achilles tendon and knee joints.

The invention is therefore based on the object of providing an outsole of the type mentioned at the outset, which makes it easier to adapt the damping ability of the outsole to different body weights of the runners without the runners having to intervene themselves. In addition, the outsole is intended to reduce the harmful peak load due to the catapult effect.

According to the invention, this object is achieved by the configuration according to the characterizing part of patent claim 1.

The fact that the damping body consists of a large number of individual bodies which are only supported in regions or points against one another in an unloaded state and which can lie directly against one another or are connected to one another by interposed elastic material, results in a progressive spring behavior. The invention is based on the principle known in principle that progressive spring detection of the elastic damping body automatically adapts it to different body weights of the runners. Because at low loads, the existing soft suspension can provide sufficient travel, while the increase in travel increases with increasing load in accordance with the progressively increasing spring detection, so that a heavy runner sinks into the outsole relatively less. In this sense, a damping body consisting of a large number of small individual bodies proves to be a surprisingly simple solution for a progressive spring behavior. This is because the individual bodies, which are preferably spheres, but can also be cubes, cylinders, cuboids or other symmetrical or asymmetrical structures, support each other loaded condition, in which they normally completely fill the recess under the heel contact surface, due to their shape only point, line or area to each other. As a result, they create gaps in the damping body formed by their entirety. As a result of these only small-area contact with one another, the load exerted on them is divided into a corresponding number of individual forces, which initially result in locally high deformation of the individual bodies. However, with increasing deformation, the contact and support surface between the individual bodies increases, so that the flexibility is getting lower. It is only at the point in time when all of the intermediate spaces are consumed by the elastic deformation of the individual bodies, ie the individual bodies are “in block”, that the damping body behaves overall like a compact elastic body with approximately linear spring detection.

The progressivity of the spring characteristic of the damping body according to the invention can be determined by choosing the size of the individual bodies. The limits of the main transverse dimension or the diameter of the individual bodies are expediently 2 and 12 mm. However, a size of 3 to 8 mm is preferred.

The progressive spring detection of the damping body which can be achieved in a simple manner in this way is accompanied by a significant further advantage of this solution. Since the individual bodies can also move relative to one another in the recess when a load occurs, part of the impressed kinetic energy is converted into friction. This has the effect that when the damping body is relieved, it does not fully return the force acting on it to the runner's heel, but only to a somewhat lesser extent. This will the normally desired catapult effect, which accelerates the runner slightly upwards as the rolling phase continues, is reduced. However, it has been shown that a fully elastic behavior of the damping body, which fully returns the previously intercepted force to the heel when relieved, can result in health problems in the heel and Achilles tendon area. The fact that the individual bodies of the damping body according to the invention only have to move back to their starting position during and after the relief - with a corresponding overcoming of friction - the above-mentioned catapult effect is taken away with a positive effect. This also applies if, for reasons of expediency, the individual bodies are easily bound to one another by an adhesive or binder for better handling during the production process of the outsole, or are even fixed to one another in one piece with and in a thin membrane. This adhesive or binding agent, which can be a silicone rubber, for example, or the membrane made of the same material as the individual body, is itself elastically flexible to a considerable extent and essentially only prevents the individual bodies from falling apart, but not their relative mobility.

As already mentioned, for the purpose of better handling, the individual bodies, for example balls, can be formed in one piece with a thin membrane, which fixes them at such a small distance from one another that there are at most tiny bridges between the individual bodies. In the case of single bodies with a curved surface on all sides, for example spheres, direct attachment of the spheres to one another is also possible in the case of fixation by means of a membrane, since the membrane can only be separated by the gaps which already exist due to the shape needs to stretch. In order not to impair the desired relative mobility of the individual bodies and the spaces formed by them, the membrane should be kept very thin, for example with a thickness of only a few tenths of a millimeter.

Instead of a membrane, the desired binding of the individual bodies to one another can also be brought about by tiny rod-shaped or ring-shaped bridges, which can likewise be produced in one piece with the individual bodies, for example by injection molding. Both the membrane and this bridge-shaped matrix can be flat or spatial. A flat design, in which the individual bodies also lie in one plane, is expedient insofar as the damping body can be constructed as a whole by several layers of these individual bodies bound in this way.

• Fig. 1 eine im Fersenbereich teilweise nach der Linie I-I in Fig. 2 längsgeschnittene erfindungsgemässe Laufsohle;
• Fig. 2 eine Draufsicht auf die Laufsohle gemäß Fig. 1, im Fersenbereich geschnitten längs der Linie II-II in Fig. 1, und
• Fig. 3 eine Einzeldarstellung eines erfindungsgemässen Dämpfungskörpers, gemäß
  der die Einzelkörper aneinander­gebunden sind.

An embodiment of the invention is explained below with reference to the accompanying drawings. The drawings show:

• 1 shows an outsole according to the invention, cut longitudinally in the heel region, partly along the line II in FIG. 2;
• Fig. 2 is a plan view of the outsole of FIG. 1, cut in the heel area along the line II-II in Fig. 1, and
• Fig. 3 is an individual representation of a damping body according to the invention, according to
  which the individual bodies are bound together.

The outsole shown in the drawings consists of a midsole 1 made of elastic plastic, e.g. Polyurethane with a Shore A hardness of 25 to 65 (corresponding to Shore-C from 40 to 80), a wear sole 2 connected to it on the running side, for example made of rubber, which may have a profiling (not shown in more detail), and a heel bed shell 3, which with the foot side of the midsole 1 is connected in the heel area and may have a Shore hardness of the same order of magnitude as the midsole or slightly above it.

A recess 4 is formed in the midsole 1 below the heel contact area, that is to say the area indicated by A in FIG extends upwards. The recess 4
ends at a distance of only about 0 to 2 mm in front of the separating surface between the heel bed shell 3 and the midsole 1. The diameter of the recess 4 is approximately 3.5 to 4 cm in the exemplary embodiment shown; their height is about 12.5 to 13 mm.

The recess 4 is provided with a plurality of small balls 5 made of an elastomeric material of high elasticity, e.g. Polyurethane or rubber, filled. The balls 5 have a largely smooth outer surface, so that they cannot get caught in one another when the load occurs, but only support one another under load or even have a certain relative mobility.

The balls 5 can, without this being clear from the drawing, before they are combined into a damping body corresponding to the shape of the recess 4 with an adhesive or binder, e.g. sprayed with a silicone rubber solution to adhere to each other and during the outsole manufacturing process, i.e. can be used as a closed damping body in the recess 4 before the wear sole 2 is applied to the midsole 1.

The recess 4 is closed on its underside by the wear sole 2. In this area, an opening 6 can be provided in the area of the recess 4, which opening is closed by a transparent plate 7 - possibly made of a harder material than the wear sole 2.

Fig. 3 shows a damping body, which consists of two spherical layers 51 and 52. Each of the two spherical layers 51, 52 is formed in that spheres 5 arranged in one plane are bound to one another by very small connecting webs 53 which are formed in one piece with the spheres, for example by injection are poured. The balls are held by this matrix of connecting webs 53 in such a way that each ball layer 52 is easy to handle. In the exemplary embodiment shown, both spherical layers 51, 52 have an essentially circular outline of a size such that they fit into the correspondingly designed recess 4 and largely fill them (FIG. 1). The upper spherical layer 51 has a sphere in the center of the circle, while the center of the lower spherical layer 52 is not occupied. In this way, the balls of the two layers are "at a gap" to each other, since the ball size is the same, so that the truncated cone-shaped structure of the damping body shown in FIGS. 1 and 3 results. The shape of the recess 4 is adapted to this structure.

In the exemplary embodiment, the balls have a diameter of approximately 7 mm, which results in a total number of approximately 40 balls of the damping body.

During the load during the run, a pressure force is exerted on the accumulation of balls 5 via the part of the heel bed shell 3 located above the recess 4 and possibly the remaining wall of the midsole 1. Starting from the center of the load, ie normally the lower apex of the heel bone, this pressure force leads to an increasing pressing of the balls 5 downwards and in the radial direction. This creates a spring travel, while due to the elasticity of the balls 5, a restoring force corresponding to the load acts. As the load increases, the reaction force of the balls progressively increases, as described at the beginning, so that the spring travel is not linear to the load, but the increase in spring travel decreases with increasing load.

Within the scope of the invention, deviations from the exemplary embodiments described above can be made. For example, the shape of the recess in which the damping body is arranged can be arbitrary and have an oval or polygonal base area instead of a circular area. Furthermore, the friction existing between the individual bodies, here balls, can be influenced in a targeted manner by deliberately keeping the surface rough or less rough. With greater roughness and thus increased friction, the balls absorb more energy and thereby reduce the force peak of the catapult effect to a greater extent. It is further understood that even when the balls are arranged in a matrix, the damping body is not limited to the design shown in FIG. 3.

Claims (8)

1. Outsole made of resilient plastic for sports shoes, with a recess (4) provided under the heel tread surface for receiving an elastically resilient damping body,
characterized,
that the damping body consists of at least two separate layers (51, 52) of individual bodies (5) that largely fill the recess (4) in their entirety and in the unloaded state with gaps only partially or point-by-point supporting each other from an elastic material, and that the individual bodies (5) are connected to one another within the respective layer (51 or 52) and the layers (51, 52) are arranged one above the other in such a way that the individual bodies (5) of one layer (51 or 52) are opposite the Individual bodies (5) of the other layer (52 or 51) are offset. 2. outsole according to claim 1,
characterized,
that the individual body (5) are balls. 3. outsole according to claim 1 or 2,
characterized,
that the main transverse dimension or the diameter of the individual body (5) is 2 to 12, preferably 3 to 8 mm. 4. outsole according to one of claims 1 to 3,
characterized,
that the individual bodies (5) are bound to one another by a binding agent or adhesive. 5. outsole according to one of claims 1 to 3,
characterized,
that the individual bodies (5) are interconnected by small webs or bridges (53). 6. outsole according to claim 5,
characterized,
that the webs or bridges (53) with the individual bodies (5) are in one piece. 7. outsole according to one of claims 1 to 6,
characterized,
that the recess (4) has the shape of a circular cylinder with an axis perpendicular to the running side of the outsole. 8. outsole according to one of claims 1 to 7,
characterized,
that the damping body has a substantially frustoconical shape and the recess (4) is adapted to the shape of the damping body.

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