DE69901005T2 - Shoe sole with double system for influencing energy - Google Patents

Description

1. Technical field of the invention

The present invention relates to a sole unit for shoes. In particular, the present invention relates to a sole unit for sports shoes that provides a so-called dual energy management system to improve the bio-mechanical properties of the shoe.

2. Background of the invention

During each contact with the ground when walking, running or jumping, forces act between the ground and the foot. These forces are usually referred to as ground reaction forces (GRF). They can be quantified using suitable measuring devices. The magnitude of the GRF is 1-1.5 times the athlete's body weight (BW) when walking. When running, the forces correspond to 2-3 BW and when jumping, forces between 5 and 10 BW have been measured.

The force-time pattern typically shows two distinct phases for any type of foot-ground interaction. An impact phase a) when the foot hits the ground, followed by a push-off phase b) in which the athlete pushes forward and upward. Fig. 1a shows the landing motion of the foot when running long distances. Approximately 80% of all runners contact the ground first with the heel. Fig. 1b shows the subsequent push-off with the middle and Forefoot area. The corresponding vertical component of the GRF is shown in Fig. 1c. As can be seen, the curve shows two clear force maxima.

The first maximum occurs after 20-40 milliseconds (ms) as a result of heel impact. In the literature, this force maximum is often referred to as the "impact force maximum" because the human body cannot react and adapt during this short interval. The second force maximum occurs after 80 ms - 100 ms and is caused by the push-off. This force maximum is often referred to as the "active force maximum" or "push-off force maximum".

These two types of forces have different consequences for the bone and muscle system:

Impact forces do not contribute to the athlete's performance. However, impact forces have been linked in a number of studies to chronic and degenerative injuries in numerous sports, particularly when the heel is affected. The aim is therefore to reduce the impact forces that occur by using suitable designs for the shoe soles. The aim is to create systems that deform slightly under load and dissipate energy in the process.

The magnitude and duration of the active forces determine the athlete's performance, ie his running speed, and the height of the jump. This means that a certain level of active forces must be maintained if the athlete wants to run at a certain speed. It is therefore the intention to support these forces. A shoe sole that allows energy dissipation so minimized as much as possible while providing the necessary damping can influence this.

Studies have shown that the relative heights of the passive and active peak values can vary depending on the sport, running speed, anatomical shape of the feet, etc. Depending on the individual case, the situation shown in Fig. 1c can change in such a way that the active peak value reaches the same size as the passive peak value, or even becomes larger. However, it is typical for two peak values to occur that are about 60 ms apart.

With regard to damping systems in the sports industry, the following approaches have been taken in the state of the art:

For example, US-A-5 695 850 discloses the concept of equipping a sports shoe with a sole unit that is intended to improve the performance of the shoe. This is to be achieved by using shoe or sole components that "recover" the energy that occurs when running and convert it into a forward movement in the push-off phase from the ground (i.e. in the area of the active peak value in Fig. 1c). For this purpose, the use of elastic materials is described either in the entire sole area or limited to the forefoot area. Suitable elastic materials include 1,4-polybutadiene/rubber compounds or - as a shoe insole - a mixture of EVA and natural rubber.

From the publication DE 87 09 757, a sole unit is known which consists of an outsole and a midsole attached to it. The midsole is formed by a relatively narrow, frame-like strip which defines a receptacle which is closed at the bottom by the outsole. Two sole parts are provided within the receptacle, one of which extends from the forefoot area of the shoe to the beginning of the heel area, in which the second sole part is provided. The first sole part preferably consists of a plastic support insert that is relatively flexible when subjected to pressure, so that when walking with the shoe on, a footbed can form on the sole part, which ensures a certain level of comfort. The sole part arranged in the heel area forms a shock absorber and is made of shock-absorbing material, such as silicone.

In a similar way, US-A-4 910 886 describes the use of shock-absorbing inserts in the heel area of a sole unit. US-A-4 316 335 discloses the use of a shock-absorbing material in both the forefoot area of a sole and the heel area, although the damping properties in the heel area are said to be better.

Finally, the publication EP 0 272 082 describes the use of a spring plate in the forefoot area of a sole unit. The spring plate has the purpose of absorbing energy during each step and releasing it again during the push-off phase.

However, all of the known solution concepts described above have the disadvantage that the proposed materials, such as material parameters for the heel and forefoot areas, are not adapted or optimized to the time course of the passive and active force peak values explained above. Furthermore, the proposed materials are not adapted to the materials otherwise used in the shoe, so that potentially competing effects are not taken into account. This in turn means that the desired effect is only partially achieved and a "spongy" or "springy" feeling occurs when running, which significantly impairs forward movement.

3. Summary of the invention

The present invention therefore poses the problem of creating an overall coordinated sole unit, in particular for sports shoes, which optimally takes into account the passive and active force peak values that occur during natural movement sequences and optimally uses the natural movement dynamics.

In addition, the sole unit according to the invention should preferably be inexpensive to manufacture and have a long service life.

According to the invention, this problem is solved by a sole unit according to claims 1, 2 and 3, respectively.

In detail, the above problem is solved by a sole unit for shoes, in particular sports shoes, which consists of at least one sole layer. The sole unit is divided according to the invention into at least two different areas from the tip to the heel (i.e. horizontal) direction. The first horizontal area extends over the forefoot area and optionally also over the midfoot area of the sole unit, whereas the second horizontal area extends over the rear foot area.

According to the invention, according to the teaching of patent claim 1, a material with predominantly elastic properties is used in the first horizontal region, which has a (material-specific) energy loss of at most 27%.

According to the teaching of patent claim 2, a material with predominantly viscous properties is used in the second horizontal region, which has a (material-specific) energy loss of at least 55%.

Finally, according to the teaching of patent claim 3, an elastic material is used in the forefoot area, which has a first energy loss, and a viscous material is used in the rearfoot area, which has a second energy loss, the difference between the second energy loss and the first energy loss being at least 28%.

In other words, the core of the present invention is the feature of providing a material layer in the forefoot area of a sole assembly that has a predominantly elastic damping characteristic. A material layer with a predominantly elastic damping characteristic has the property during forward movement that the repulsion from the ground is supported by the "elastic backscattering" of the kinetic energy.

In contrast, according to the invention, a material layer that has a predominantly viscous damping characteristic is preferably used in the rear foot area of the layered ensemble of the sole (the heel area). The use of a viscous material leads to a "recoil-free" absorption of the shocks that occur when running, especially on the heel of the foot, since the shock energy is converted into heat.

The elastic and viscous materials used in the invention are characterized by their material-specific energy loss. The inventors of the present invention have found that the critical material size in providing the optimal materials for the rear foot area and the Forefoot area is the energy loss to be determined experimentally. The energy loss is the value that results from the response behavior of a test material when subjected to a dynamic force field. In order to be able to determine the response behavior in a biomechanically adapted manner, a method according to the invention is used, according to which a sample of the material to be tested is subjected to a dynamic force field, the course of which corresponds to the force field that acts on the feet when humans walk or run. Preferably, the GRF force profile shown in Fig. 1c (separately for the forefoot and rearfoot areas) is applied to the test material.

A certain amount of energy is fed into the materials via this GRF force profile, which leads to a deformation of the material body. This deformation is reduced again by the material-specific elastic properties with a certain time behavior, thus leading to energy recovery. However, for physical reasons, the energy recovered in this way is always smaller than the energy fed in, since part of the energy fed in is converted into heat depending on the material. If you calculate the difference between the energy fed in and the energy recovered, you get a positive difference that can be described as "energy loss".

It has now been shown according to the invention that elastic materials suitable for the forefoot area may have an energy loss of no more than 27% in order to lead to measurable support in the upward and forward movement of the foot in the push-off phase of the foot.

Furthermore, it has been shown that the viscous materials used in the rear foot area for shock absorption must have an energy loss of at least 55% in order to lead to a measurable reduction in the risk of injury.

Finally, the invention has shown that a combination of elastic and viscous materials in the forefoot and rearfoot areas, which have an energy loss difference of at least 28%, results in a combination effect that leads to increased performance of the athlete, since running (or walking) leads to reduced energy consumption. This was determined experimentally in comparative studies on the respective oxygen consumption of the athletes.

Preferably, the first horizontal region is the forefoot region and the second horizontal region is the rearfoot region of the sole unit, wherein the first and second horizontal regions of the layer ensemble can be arranged either in the same transverse layer according to a preferred embodiment (claim 4) or, according to a further preferred embodiment, in two different transverse layers (claim 5).

A further advantageous embodiment of the present invention provides, in addition to the layer or layers with the elastic and viscous regions, further layers in the sole unit, such as an insole and an insole or outsole. If such additional layers are used, it is advantageous to take into account a further material constant, namely the dynamic stiffness of both the elastic and the viscous material in comparison to the dynamic stiffnesses of the materials that form the further layers of the sole unit. The dynamic stiffness (Dynamic Stiffness) is the slope of the curve in the deformation-force diagram at certain force intervals (preferably between 1000 N and 1500 N, and between 200 N and 400 N).

The inclusion of dynamic stiffness in designs in which the sole unit consists of several layers is important because if the materials are chosen incorrectly, the elastic properties in the forefoot area and the viscous properties in the rear foot area are not effective. One can imagine the situation as it is with two springs coupled in series. The effect of spring 1 with specially adapted spring characteristics is not effective if the spring constant of the second spring is smaller than that of the first. In this case, the damping behavior of the coupled springs is determined primarily by spring 2. The first spring only becomes effective when spring 2 is (fully) compressed.

For this reason, in the preferred embodiment according to patent claims 7 and 8, it is proposed to provide optionally present additional layers of the sole unit with a dynamic stiffness that is greater than that of the viscous material or the elastic material. For the viscous materials, this is particularly relevant for forces between 200 N and 400 N.

The advantageous embodiments according to patent claims 9 to 11 are, according to the invention, sole units which are preferably used in field sports (patent claim 9), in running shoes (patent claim 10) and in universal shoes (patent claim 11).

The elastic plastic preferably used in the forefoot area according to the invention comprises 50 vol.% ethylene vinyl acetate (EVA) and 50 vol.% natural rubber (claim 13).

Finally, the viscous material preferably used in the rear foot area according to the invention comprises a butyl polymer (patent claim 14).

It has been shown that these plastics meet the requirements of a layer ensemble according to the invention particularly well. They are therefore ideally suited as materials for the dual energy management system according to the invention.

4. Brief description of the drawings

Preferred embodiments of the present invention will now be explained with reference to the drawings, in which:

Fig. 1 the natural movement of a foot during running (Fig. 1a-b), and the resulting GRF force profile (Fig. 1c);

Fig. 2a shows a force-time diagram of two force fields exerted by a measuring device according to the invention on the heel area and the forefoot area of sole units or material layers according to the invention in order to determine the energy loss according to the invention and the dynamic stiffness;

Fig. 2b shows a measuring device according to the invention as used for applying the force profiles shown in Fig. 2a and for measuring the resulting deformation (and thus the energy loss and the dynamic stiffness);

Fig. 2c the force stamps used in the device according to Fig. 2b for the heel area and the forefoot area;

Fig. 3 the deformation behavior of a viscous material with the resulting energy loss (hatched) and the dynamic stiffness DS between 1 KN and 1.5 KN;

Fig. 4 the deformation behavior of an elastic material with the resulting energy loss (hatched) and the dynamic stiffness DS between 1 KN and 1.5 KN;

Fig. 5 shows a sole layer according to the invention according to a preferred embodiment, in which an elastic material is used in the forefoot area and a viscous material is used in the rear foot area;

Fig. 6a is a section along the line A-A (or B-B) of Fig. 5, in which a preferred embodiment of the sole unit according to the invention is shown; and

Fig. 6b is a section along the line A-A (or B-B) of Fig. 5, in which a further preferred embodiment of the sole unit according to the invention is shown.

5. Detailed description of the preferred embodiments

The presently preferred embodiments of the present invention are described below with reference to the drawings.

In Fig. 1, a human foot is shown with a shoe 10, which essentially consists of an upper 20 and a sole unit 50. As will be explained in detail, the sole 50 preferably consists of a plurality of layers, which are referred to below as a layer ensemble.

In order to explain the principles of the invention, a foot in its natural movement sequence when walking or running is first explained in more detail with reference to Fig. 1.

As shown in Fig. 1a and already mentioned in the introductory part, for around 80% of people the movement sequence in a step sequence begins with the heel area of the foot touching the ground. At this point, the human musculoskeletal system experiences a strong burst of force. In the subsequent phase of the rolling movement, the acting force initially decreases again until it increases again at the moment of push-off (see Fig. 1b). Therefore, the force-time diagram is a curve with two maxima.

If, to confirm the above consideration, a test person is asked to perform the movement process typical for running on a force-time measuring platform, the force profile shown in Fig. 1c is obtained. A force equivalent (in multiples of body weight) is plotted on the ordinate and the time in milliseconds on the abscissa. The diagram shown in Fig. 1c is also called a GRF diagram (since the forces acting on the foot during a step are also called ground reaction forces (GRF) - as mentioned in the introduction).

As can be seen from Fig. 1c, the GRF curve shows a first sharp maximum after about 20-40 ms, which results from a rapidly increasing force, which in the example shown in Fig. 1c corresponds to about 2.5 times the weight force. As already mentioned in the introductory part, this first peak value is also called the vertical force peak value (VFIP value). The phase shown in Fig. 1c from t = 0 to t = A (around 30 ms - 50 ms) in the GRF diagram is called the passive phase. It corresponds to the impact of the heel area of the foot on the ground (see Fig. 1a).

The passive phase of the movement process is followed by the so-called active phase in the GRF diagram. The renewed increase in force in the active phase is based on the push-off process of the foot from the ground (see Fig. 1b). The force impulse that occurs here and acts on the musculoskeletal system is considerably smaller, as the build-up of force occurs more slowly than in the passive phase (approximately 80 ms - 100 ms). The course of the GRF diagram can vary considerably in individual cases depending on the boundary conditions (running speed, foot anatomy, hardness of the ground, etc.).

Since the increase in force in the passive phase occurs much faster than in the active phase, it also leads to a higher load on the heel, since the The impulse (force impulse) acting on the body is correspondingly greater. In addition, when hitting a hard surface, the impulse is "reflected" by the ground, so that it has to be absorbed by the anatomy. This leads to significant injuries and wear and tear, particularly in the case of long-term stress (such as marathon running).

In comparison, the load on the forefoot area is correspondingly lower due to the lower force impact (longer power build-up time). In addition, it has a larger surface area and an anatomical design that allows for better internal body cushioning.

For this reason, the invention concluded that the heel area requires better protection than the forefoot area in order to avoid anatomical damage. Since the forces in the forefoot area build up more slowly, the foot is better able to adapt to the increase in load (which is lower here).

However, it is advantageous for the forefoot area to have a sole property that reflects the component of the force impulse pointing in the direction of travel or upwards in the direction of travel and/or away from the ground. For illustration, please refer again to Fig. 1b. If kinetic energy is transferred back to the foot when the forefoot comes into contact with the ground, this leads to the foot being pushed off the ground, thus supporting the forward movement.

The present invention is therefore based on the knowledge that materials with different properties can be provided in the heel area and in the forefoot area of a sole unit: In the forefoot area, an elastic material is used, while in the heel area a viscous material is preferred.

Now, there are no purely elastic or viscous materials in nature; there is always a combination of these two properties. For the purposes of the present invention, elastic and viscous materials are therefore strictly speaking understood to mean materials with elasto-viscous properties in which one or the other property is more or less pronounced.

According to the invention, an "elastic" material is understood to mean a material that is predominantly elastic, i.e. has only a small amount of viscous properties. In the sense of the present invention, a "viscous" material is understood to mean a material that is predominantly viscous, i.e. has only a small amount of elastic properties.

Elastic here means that the materials spring back elastically under the influence of force fields or impacts and, ideally, completely release the energy absorbed by the impact. Materials with viscous properties, on the other hand, are materials that convert a large part of the absorbed energy into heat, i.e. they only deform slightly elastically.

Therefore, if a viscous material in the sense of the invention as described above is used, preferably in the heel area of a sole unit, it has the property of converting the force transmitted by the heel at least partially into heat and in this way preventing the force from being "reflected" by the ground and putting pressure on the heel. As a result, subjectively from the runner's point of view, a very "soft" running feeling is achieved.

In contrast, the predominantly elastic material used in the forefoot area has the property of pushing the foot off the ground and, as it were, "catapulting" the runner forward, as it reflects the force from the ground.

From the above considerations it is clear that the energy loss occurring during deformation is particularly suitable for the inventive characterization or quantification of viscous and elastic materials. This value (measured in %) describes the ratio of the energy fed into the material via the force field to the energy recovered during relaxation.

In order to be able to determine the energy loss of suitable materials that is essential for the present invention, a device is used according to the invention, which is shown in Fig. 2b. The device consists of a platform 5 on which the material to be examined is located. This material can be in the form of a single layer of material (preferred) or - as shown - as a finished sports shoe. In any case, it is preferred that the material to be examined is provided in the same thickness and preferably in the same form in which it will later be used in the shoes. A defined force field is then applied to the material to be examined using a stamp arrangement 7 via a stamp 8 (to be described in more detail below) (see Fig. 2c). Below the platform 5 there is a (schematically shown) measuring arrangement 6 with which the resulting deformation of the test material (in mm) is measured. The structure of the stamp arrangement 7 and the measuring arrangement 6 is known to the person skilled in the art and does not need to be described further here. A corresponding device, with the exception of the stamps 8 described below, is commercially available under the name INSTRON test machine test setup 8502 from INSTRON Ltd, High Vycoms, Great Britain.

The force field applied with the aid of the stamp arrangement 7 or the stamp 8 has, according to the invention, different profiles for examining the elastic and viscous materials according to the invention in order to simulate the actual conditions as realistically as possible. Accordingly, a force field is used for examining suitable viscous materials, which is designated as "heel" in Fig. 2a. In order to simulate as realistically as possible, a stamp 8a is also used, the geometry of which is close to that of a human heel. The stamp 8a has a circular cross-section with a diameter of 5 cm and a cross-sectional area at its lower end of 19.63 cm² (which is slightly curved). In contrast, a force profile is used for measuring suitable elastic materials, which is designated as "forefoot" in Fig. 2a. The stamp 8b used for these measurements is adapted in terms of its geometry to the human forefoot. Stamp 8b has an elongated shape with a length of 8.5 cm and a width of 5 cm. Its (again slightly curved) underside has a cross-sectional area of 42.50 cm². Finally, the materials were examined in a thickness that is usually found in real shoes (1 mm in the forefoot area; 20 mm in the rear foot area)

In the following, the test results measured with the aid of the measuring device 6, 7 according to the invention (cf. Fig. 2b) are discussed with reference to Figs. 3 and 4.

Fig. 3 shows the deformation behavior of a viscous material according to the invention, which is subjected to the force profile designated "heel" in Fig. 2a using the device shown in Fig. 2b, with the deformation measured with the device 6 being shown on the abscissa, depending on the force field applied with the stamp 7. As can be seen from the figure, the viscous material preferably used in the heel area shows a strongly pronounced hysteresis behavior. When the force is built up according to the force profile "heel" from Fig. 2a, a deformation occurs that only slowly increases over time. reforms again, and does so with a considerably lower counterforce on the stamp 8a. The resulting energy loss can be determined graphically or numerically and is shown as a hatched area in the diagram. As can be seen, with the viscous material according to the invention, a considerable proportion of the energy fed in is converted into heat and is no longer available as a restoring force when the material returns to its original shape.

In addition to the energy loss, the graph in Fig. 3 also shows another value that is important for the present invention, namely the dynamic stiffness (DS) of the material being examined. The dynamic stiffness is defined as the ratio between the acting force F [N] and the resulting deflection d [mm]. Experiments have shown that two areas of dynamic stiffness are of particular interest for sports shoes: the stiffness between 1000 N and 1500 N, and the stiffness between 200 N and 400 N. It is calculated as follows:

Dynamic stiffness DS10000-115500 = (F1500N - F10000N)/(d15500N - d1000N) [N/mm]

The value for the dynamic stiffness between 200 N and 400 N is determined accordingly; it is not shown graphically in Fig. 3.

According to the invention, the dynamic stiffness is of interest in sole units that consist of a layer ensemble (ie of a plurality of layers made of different materials). In such arrangements (which can comprise, for example, an inner layer, a middle layer, the functional layer according to the invention - referred to below as functional layer(s) - and an outsole), the effect described above only occurs occurs when the stiffness of the functional layer in the force ranges of interest is not higher than that of the materials from which the other layers are made. The materials used in the sole area in particular are EVA (ethyl vinyl acetate) and PU (polyurethane) because of their ease of processing and low cost. So that the elasto-viscous properties of these materials do not determine the overall behavior of the sole, it is necessary that the dynamic stiffness of the viscous and elastic materials according to the invention is lower than that of these materials.

In contrast, Fig. 4 shows the response behavior of the elastic material according to the invention. As can be seen from Fig. 4, the elastic material only shows a very weak hysteresis behavior, and thus only a very small energy loss according to the invention. The material relaxes almost simultaneously with decreasing force, whereby essentially the energy fed in via the force stamp 8b is also released again. Here, too, the value for the dynamic stiffness between 1500 N and 1000 N is shown graphically (the corresponding value for the dynamic stiffness between 400 N and 200 N was again omitted for the sake of simplicity).

In extensive investigations related to the present invention, it has now been found that in order to achieve the success according to the invention, certain values must be achieved both for the energy loss in the elastic and viscous material and (in the case of shoes with several layers made of different materials) for the dynamic stiffness DS. These values that can be achieved according to the invention are summarized in the following table:

As can be seen, the energy loss that occurs with the elastic materials according to the invention should be at most 27%. In contrast, the energy loss that occurs with the viscous material according to the invention should be at least 55%. Comparative studies have shown that with the resulting minimum energy loss difference of 28% between the forefoot and the hindfoot, on the one hand, a considerable reduction in the risk of injury in the area of the vertical force peak value is achieved, and on the other hand, the stored energy is released optimally in the area of the active peak value. The result is a shoe that is not only very comfortable to wear and without risk of injury, but also increases the athlete's performance. Comparative studies with conventional shoes have shown that athletes wearing the shoes according to the invention showed a reduced oxygen requirement when running a test track.

The situation is somewhat more complex when it comes to the values for dynamic stiffness: the picture varies depending on the sport, as different sports place different demands on the shoe. It was found that for field sports (basketball, volleyball, football) the dynamic stiffness between 1000 N and 1500 N should be less than 600 N/mm for the elastic material and less than 250 N/mm for the viscous material.

For running shoes, however, the dynamic stiffness of the elastic material should be less than 450 N/mm between 1000 N and 1500 N, and the dynamic stiffness of the viscous material should be less than 200 N/mm.

For a universal shoe, the following represents a good compromise: the dynamic stiffness of the elastic material should be less than 600 N/mm between 1000 N and 1500 N and less than 300 N/mm between 200 N and 400 N; that of the viscous material should be less than 250 N/mm between 1000 N and 1500 N and less than 130 N/mm between 200 N and 400 N.

Accordingly, the following materials are suitable for the purposes of the present invention:

Table 1: Elastic material I. Material parameters (VGB-1A)

Energy loss (%) 24.5%

Stiffness (200 N - 400 N) 230 N/mm

Stiffness (1000 N - 1500 N) 440 N/mm

Max. deformation 61%

Durometer 52 Asker C

Specific gravity 0.28 g/cm³

Elasticity* 57%

*: Measured according to DIN 53512

The preferred material VGB-1A is a substance with the following composition:

EVA (21%): 50 phr

Isoprene rubber: 50 phr

RB-500 6phr

Stearic acid: 0.8 phr

T4: 1phr

Zinc stearate: 1.2 phr

Zinc oxide: 2 phr

Dicumyl peroxide: 0.6 phr

Blowing agent: 3.5-5.0 phr

Pigment: X (depending on color)

The term phr is a unit of quantity (parts per hundred parts of rubber) for additives that are added to rubber for "formulation". (see also Römpp Lexikon Chemie - Version 1.3, Stuttgart/New York: Georg Thieme Verlag 1997).

However, this elastic material according to the invention only represents the currently preferred embodiment. According to the invention, the EVA/rubber proportions can also be varied: It is also possible to use 40 to 60% by volume of ethylene vinyl acetate (EVA) and 60 to 40% by volume of natural rubber. This material has excellent elastic properties on the one hand and can also be easily and inexpensively formed into shoe soles using standard molding processes.

However, the best results can currently be achieved by using the elastic material 1 (VGB-1A) described above in the specified composition. It is expressly pointed out that the mixing ratios specified above do not mean that other additives cannot be added to the mixture (for example to influence the color).

According to a further embodiment of the invention, another elastic material can be used as follows:

Table 2: Elastic material II. Material parameters (VGB-7A)

Energy loss (%) 27%

Stiffness (200 N - 400 N) 210N/mm

Stiffness (1000 N - 1500 N) 480 N/mm

Max. deformation 61%

Durometer 52 Asker C

Specific gravity 0.28 g/cm³

Elasticity 55%

The material VGB-7A is a substance with the following main components:

Eva 462: 60 phr

IR (rubber): 30 phr

Engage 003: 10 phr

RB-500: 6phr

According to the present invention, the following materials are particularly to be used as viscous materials:

Table 3: Viscous material I. Parameters Material (B-HD45)

Energy loss (%) 65%

Stiffness (200 N - 400 N) 120 N/mm

Stiffness (1000 N - 1500 N) 200 N/mm

Max. deformation 60%

Durometer 45 Asker C

Specific gravity 0.42 g/cm³

Elasticity 10%

The material B-HD45 is a substance with the following composition:

Butyl polymer: 100 phr

Filling material: 30 phr

Activator: 1 phr

Dicumyl peroxide: 4 phr

Antioxidant: 1 phr

Polymeric plasticizer: 3 phr

Blowing agent: 4 phr

B-HD45 is supplied as a flat stock material and subsequently processed into a desired sole layer.

Alternatively, another viscous material with Buty polymer and Norsorex (a type of rubber) as main components, the following material can be used:

Table 4: Viscous material II. Parameters Material (BIM-50)

Energy loss (%) 65%

Stiffness (200 N - 400 N) 120 N/mm

Stiffness (1000 N - 1500 N) 200 N/mm

Max. deformation 60%

Durometer 50 Asker C

Specific gravity 0.42 g/cm³

Elasticity 10%

The BIM-50 material is the same as the B-HD45 material described above in terms of its composition. The difference, however, is that BIM-50 has been compression molded to form the sole layer.

In comparison to the elastic and viscous materials according to the invention, the parameters essential to the invention of the previously known EVA are given in the following table for comparison purposes.

The first table shows the data for typical EVA processed for a forefoot portion of a sole structure, while the second table (Table 6) reflects the data for a typical EVA processed for use in a rearfoot portion of a sole structure.

Comparison table for Table 5: EVA (forefoot) Parameters Material (EVA)

Energy loss (%) 33+/-2%

Stiffness (200 N - 400 N) 260+/-20 N/mm

Stiffness (1000 N - 1500 N) 520+/-20 N/mm

Comparison table for Table 6: EVA (rear foot) Parameters Material (EVA)

Energy loss (%) 38+/-2%

Stiffness (200 N - 400 N) 120+/-20 N/mm

Stiffness (1000 N - 1500 N) 220 +/-20 N/mm

Taking into account the inventive materials discussed in detail above, preferred embodiments of a sole unit according to the invention are shown in Figs. 5 and 6.

Fig. 5 shows a sole according to the invention in horizontal section. Shown is the outsole 50 of the shoe 10, which is divided into a forefoot area 60 and a rear foot area 80. The sole 50 can in turn consist of a plurality of individual layers, as is usually the case with sports shoes. For example, the sole can consist of an outsole 55, a midsole 59 and an insole (not shown) (see Fig. 6a).

According to a preferred embodiment, the functional layer 57 according to the invention is located between the outsole 55 and the midsole 59. The functional layer 57 according to the invention can be divided into two horizontal areas according to the present invention: namely the forefoot area 60, which consists of a predominantly elastic material according to the invention, and the heel area 80, which consists of a predominantly viscous material. A further transition area 70 can be provided between these two horizontal areas. However, this is not necessarily necessary; the forefoot area 60 and the rearfoot area 80 can also directly abut one another.

According to an alternative embodiment of the present invention (not shown), two functional layers 57 can also be provided. In this case, the first functional layer in the forefoot area has the elastic material according to the invention, and the second functional layer in the heel area has the viscous material according to the invention.

As can be seen from Fig. 6a and 6b, the functional layer 57 according to the invention can, according to two preferred embodiments, extend laterally slightly over the midsole 59 (Fig. 6a), or to a considerable extent. This depends on the area of application of the sports shoe. Where the probability of the foot hitting the ground sideways is high (in all sports where jumping occurs more frequently), the embodiment according to Fig. 6b is preferred. In contrast, the embodiment according to Fig. 6a is preferably used, for example, in running shoes.

As far as the materials to be used preferably according to the present invention are concerned, both elastic and viscous materials are known in principle in the prior art. However, the materials used should preferably have special properties in order to qualify as sole material for sports shoes.

According to the present invention, the materials should be easy to form using common processes, be lightweight and have high tear and abrasion resistance. For this reason, many of the known materials (such as natural rubber as an elastic material) are not suitable.

It has been particularly stated that the scope of the present invention is not limited to the preferred embodiments discussed above. In particular, all obvious changes in the features are intended to be included. For example, in the above description of the preferred embodiments of the present invention, it has been suggested that different material compositions are preferably used to change the preferred stiffness of the various sole layers. The same result can be obtained if the thickness of the sole or Partial areas thereof can be suitably adapted. Furthermore, the materials according to the present invention do not have to form the entire forefoot area or rearfoot area. Alternatively, small pieces thereof can be inserted into the corresponding sole areas.

Claims (15)

1. Sole unit for shoes, in particular sports shoes, which comprises at least two regions in the horizontal direction, the first region (60) extending over the forefoot region and the second region (80) over the rear foot region, the first region comprising an elastic material which has an energy loss of at most 27%. 2. Sole unit for shoes, in particular sports shoes, which comprises at least two regions in the horizontal direction, the first region (60) extending over the forefoot region and the second region (80) over the rear foot region, the second region comprising a viscous material which has an energy loss of at least 55%. 3. Sole unit for shoes, in particular sports shoes, which comprises at least two regions in the horizontal direction, the first region (60) extending over the forefoot region and the second region (80) over the rear foot region, the first region (60) comprising an elastic material having a first energy loss and the second region (80) comprising a viscous material having a second energy loss, the difference between the second energy loss and the first energy loss being at least 28%. 4. Sole unit according to one of the preceding claims, in which the first (60) and second (80) horizontal region are arranged in a layer (57) of the sole unit (50). 5. Sole unit according to one of the preceding claims 1 to 3, in which the first (60) and second (80) horizontal regions are arranged in two different layers (57) of the sole unit (50). 6. Sole unit according to one of the preceding claims 4 or 5, which, in addition to the layer or layers (57) with the elastic material and the viscous material, comprises at least one further layer, such as in particular an outsole layer (55) and/or an insole layer (59). 7. Sole unit according to claim 6, in which the further layer or layers (55, 59) have a dynamic stiffness, and the dynamic stiffness of the elastic material is equal to or less than the dynamic stiffness of the further layer or layers (55, 59). 8. Sole unit according to claim 6, in which the further layer or layers (55, 59) have a dynamic stiffness, and the dynamic stiffness of the viscous material between 200 N and 400 N is equal to or less than the dynamic stiffness of the further layer or layers (55, 59). 9. Sole unit according to one of the preceding claims 1 to 6, in which the dynamic stiffness of the elastic material between 1000 N and 1500 N is less than 600 N/mm, and the dynamic stiffness of the viscous material is less than 250 N/mm. 10. Sole unit according to one of the preceding claims 1 to 6, in which the dynamic stiffness of the elastic material between 1000 N and 1500 N is less than 450 N/mm, and the dynamic stiffness of the viscous material is less than 200 N/mm. 11. Sole unit according to one of the preceding claims 1 to 6, in which the dynamic stiffness of the elastic material between 1000 N and 1500 N is less than 600 N/mm and in which the dynamic stiffness of the viscous material between 1000 N and 1500 N is less than 250 N/mm and between 200 N and 400 N is less than 130 N/mm. 12. Sole unit according to one of the preceding claims, in which the elastic material comprises: a. 50 to 70 vol% ethylene vinyl acetate (EVA), and b. 50 to 30 vol% natural rubber. 13. Sole unit according to one of the preceding claims 1 to 11, in which the elastic material comprises 50 vol% ethylene vinyl acetate (EVA) and 50 vol% natural rubber. 14. A sole unit according to any preceding claim, in which the viscous material comprises a butyl polymer and Norsorex. 15. Sole unit according to one of claims 1 to 14, in which the viscous material comprises 100 phr of a butyl polymer, 30 phr of a filler, 1 phr of an activator, 4 phr of a dicumyl peroxide, 1 phr of an antioxidant, 3 phr of a polymer plasticizer, and 4 phr of a blowing agent.