EP0875164B1 - Energy-storing shoe-bottom construction for security shoes - Google Patents

Abstract

The lower shoe construction is designed especially for safety shoes. The heel includes an energy absorber (16) to protect against impulse- or mechanical shock injuries in the heel or ankle regions. The device has a stiff, elastic deformation characteristic, with a force/distance function having a steeply-rising onset and subsequently degressive form. Preferably, the energy absorbent material is an insert embedded in a soft elastic substance, especially polyurethane, used in the sole construction. The insert is hollow and made of two parts, joined together. It may be made in an injected plastic with hardness of 60-70 Shore-D, using e.g. polyamide, polypropylene and/or polyoxymethylene.

Description

The invention relates to a shoe substructure, especially for safety shoes, with a sole construction with one to protect against impulses or impacts Injuries arranged in the heel or heel area Energy absorption element a flat, about disc-like hollow body with a circular contour has first wall and a second wall, the second wall, bowl-shaped, in particular frustoconical is formed, the shell-shaped second wall a flat-conical circumferential section and one centric, flat, integral with the Connected peripheral portion and to one by the Sole structure in the heel area defined foot contact area has approximately parallel central section and that the two walls of the hollow body as separate Molded parts formed and in the area of their peripheral edges - preferably via a positive or non-positive Snap connection - so tightly connected are that the internal cavity of the embedded, in particular with PU-foamed hollow body free of that surrounding material of the elastic sole layer is.

Footwear for the commercial sector is meant to be in case falls to protect against impact-related injuries, in particular heel fractures, an energy absorbing Show shoe base. For energy absorption the European standard EN 344 requires a value of 20 Joules, while the previous national DIN 4843 had a value of 30 joules. The different values are on the one hand due to the fact that so far in certain Countries faced technical problems with the higher value to reach. On the other hand, it is also due to different ones Measuring methods, which are in the standards for detection energy consumption are described. in principle but it can be assumed that an energy intake of at least 30 joules provides better protection than 20 Joule.

A shoe substructure of this type is known for example from EP-A-0 749 705. This well-known Construction has already proven itself quite well, because they are both comfortable to wear and a good energy absorption capacity of about 30 joules (measured according to EN 344, section 5.10). This is a made of relatively soft elastic material Damping element with a relatively harder, but nevertheless also elastically compressible material existing energy absorption element combined. 0

A shoe substructure according to the generic term is over WO 81/03602 known. It includes two in series switched, hollow-tapered spring elements that such are built up and embedded that a progressive suspension characteristics results.

The object of the present invention is now based on the energy consumption behavior at the same time good comfort to improve even further, while also an economical production process can also be possible should.

This object is achieved with a shoe substructure achieved according to the generic term that the first wall is flat is. As a result, the energy absorption element has a stiff elastic deformation behavior with a Force / path characteristic that is initially steep increasing and gradually declining Has initial section. This invention Energy absorption element is preferred as a flat one Insert part designed and in a soft elastic Material (in particular PU existing sole layer embedded) so that by overlaying the Force / displacement characteristics of the rigid energy absorption element and the soft elastic sole view a resulting characteristic curve arises in such a way that the from the surface and the resulting characteristic resulting energy in the range of about 30 to 40 joules, in particular around 35 joules.

The invention is based on the knowledge that it is common with elastic materials because of them Deformation behavior at most with special, complex measures is possible, an energy intake to reach over 30 joules. Because such elastic compressible materials typically have one progressive characteristic curve with a relatively flat initial increase. Because the energy (or work) from the area below the force / displacement characteristic curve (displacement integral of the force), becomes the first part of the total deformation path with only low energy consumption, so practical wasted. Because the maximum in the sales area of shoes possible deformation path with about 15 mm extremely anyway is low, that is enough after the flat rise remaining path despite the then progressive increase no longer looking to still target the energy value to come from about 30 joules.

This disadvantage of the usual elastic materials is now compensated for by the energy absorption element according to the invention, in that the steep, possibly initially progressively increasing initial section of its force / displacement characteristic curve already ensures a high energy absorption in the first region of the deformation path of the sole structure, because in this region the area ( = Energy) is significantly increased under the resulting characteristic compared to the typical characteristic of an elastic material. The energy absorption element according to the invention can advantageously be designed so that a resulting characteristic curve arises in the overall effect of the sole structure, which increases very quickly to a maximum permissible force when deformed and retains approximately this value of the force when deformed further. In theory, almost the maximum energy could be absorbed as a product of power. For ergonomic reasons, the maximum permissible force should be around 5,000 N; this value represents approximately the maximum force that a human heel bone can withstand without breaking. If a deformation path of about 15 mm is assumed, then theoretically an energy of 5,000 N 0.015 m = 75 Nm (J) could be absorbed if the force / displacement characteristic suddenly jumped to the value F _max at the origin and over the entire Deformation path s _max would remain constant. Of course, this value cannot be achieved in practice, but the invention does succeed in achieving values significantly higher than 30 joules.

The special characteristic of the energy absorption element according to the invention is achieved constructively in that the Energy absorption element from a flat, in particular with a circular contour like a disc-like hollow body with a first, e.g. lower, i.e. one Bottom of the sole (profile side) facing wall and a second, e.g. upper, a shoe upper facing wall is formed, one of the two Walls curved essentially in a bowl shape, in particular frustoconical and the other flat is trained. The bowl-shaped wall needed for Deformation due to a kind of arch effect at first a relatively high force (steep rise in the characteristic curve), and after a certain deformation path the increase then correspondingly flatter; it can even be achieved that the characteristic curve climbs steeply and then degressively flattening initial section subsequent, sloping curve section. The bowl-shaped or frustoconical shape acts for this Wall of the hollow body according to the principle of an Children's toy known "crack frog" (jumping around Leaf or plate spring) with the just formed Wall together advantageously. Through this curve becomes in cooperation with the surrounding soft Sole material and its very much in this area achieved a much steeper curve that the resulting characteristic curve over the further deformation path remains at about the maximum force.

Further advantageous design features of the invention are in the subclaims and the following description contain.

Fig. 1

einen Längs-Vertikalschnitt durch einen Schuh, der eine erfindungsgemäße Unterkonstruktion aufweist,

Fig. 2

eine Seitenansicht eines erfindungsgemäßen Energieaufnahmeelementes in Kombination mit einer nur bereichsweise dargestellten Stahl-Zwischensohle,

Fig. 3

eine Draufsicht in Pfeilrichtung III gemäß Fig. 2,

Fig. 4

einen Schnitt durch das Energieaufnahmeelement in der Ebene IV-IV gemäß Fig. 3 (entspricht dem Schnitt in Fig. 1),

Fig. 4a

eine Darstellung analog zu Fig.4, jedoch in einer Ausführungsvariante des Energieaufnahmeelementes,

Fig. 5

ein schematisches Kraft/Weg-Diagramm zur Erläuterung der Wirkungsweise der Erfindung, und

Fig. 6 und 7

zwei weitere Ausführungsformen der Erfindung.

The invention will be explained in more detail below with reference to preferred exemplary embodiments shown in the drawing. Show:

Fig. 1

a longitudinal vertical section through a shoe having a substructure according to the invention,

Fig. 2

2 shows a side view of an energy absorption element according to the invention in combination with a steel midsole which is only shown in sections,

Fig. 3

3 shows a plan view in the direction of arrow III according to FIG. 2,

Fig. 4

4 shows a section through the energy absorption element in the plane IV-IV according to FIG. 3 (corresponds to the section in FIG. 1),

Fig. 4a

4 shows a representation analogous to FIG. 4, but in an embodiment variant of the energy absorption element,

Fig. 5

a schematic force / displacement diagram to explain the operation of the invention, and

6 and 7

two further embodiments of the invention.

The same parts are in the different figures of the drawing always be provided with the same reference numerals therefore usually only described once.

1 shows a safety shoe 1 in section, which consists of an upper shoe 2 and a substructure 4. The substructure consists essentially of a sole structure 6, which in turn is a conventional profile sole 8 and one made of soft elastic material Has sole layer 10. In this sole layer 10 is with such safety shoes usually a steel midsole 12 embedded. This steel midsole serves as a puncture-proof insert (e.g. according to DIN 32768), around the foot, especially in the construction area in front of pointed objects, such as nails, etc. Towards the upper shoe 2 adjoins the elastic sole layer 10 an insole 14.

The sole structure 6 is in the heel or heel area equipped with an energy absorption element 16. The present Invention is particularly concerned with the design and arrangement of this energy absorption element 16, which now in particular with reference to FIGS. 2 to 4 or 4a to be explained in more detail.

Is in the embodiment shown in Figs. 2 to 4 the energy absorption element 16 as a flat insert trained and in particular made of polyurethane (PU) existing sole layer 10 embedded. This insert part is of a flat, preferably with a circular contour (see Fig. 3) approximately discus-like (Fig. 2,4 and 4a) Hollow body 18 formed. This hollow body 18 consists of a first, lower in this embodiment, the Bottom of the sole (profile side) facing wall 20 and a second, here upper, facing the shoe upper 2 Wall 22. The first wall 20 is preferably in the essentially flat, while the second wall 22 has an approximately cup-shaped contour. This will enclosed a cavity 24 between the two walls 20, 22. The shell-shaped second wall 22 preferably has the shape of a truncated cone with a flat-conical Circumferential section 26 and a central, in essential plane center distance 28. This middle section 28 runs approximately parallel to one through the Sole structure 6 in the heel area defined footrest area; see Fig. 1.

4 and 4a, the two walls 20, 22 of the Hollow body 18 preferably formed as two separate molded parts and here in the region of their peripheral edges - preferably via a positive or non-positive snap connection 30 (in the manner of a can lid closure) - so closely connected that the inner cavity 24 embedded in the elastic sole layer 10 according to FIG. 1 Hollow body 18 when embedding or foaming free of the surrounding material of the sole layer 10 remains. This prevents the deformation behavior influenced by material penetrating into the cavity 24 becomes.

The snap connection 30 is shown in FIG. 4 by a circumferential Edge web 32 of the first wall 20 is formed, wherein the upper wall 22 engages latching in the edge web 32. In the case of FIG. 4a, both walls 20 and 22 each have an edge web 32 or 32a, which interlock with one another.

Because of this embodiment of the invention described so far Energy absorption element 16 has this a force / displacement characteristic curve illustrated in FIG. 5 with a initially steeply rising and then degressive flattening initial section 34. At this initial section 34 is followed by a second curve section 36, the - as shown - preferably a sloping course has. This second curve section 36 of the force / travel characteristic of the energy absorption element 16 then goes finally into a progressively increasing end section 38 over.

5 is for comparison with that by a continuous Line illustrated characteristic of the invention Energy absorption element 16 also dashed a usual Characteristic curve 40 of an elastically compressible material shown. This characteristic curve 40 has a clearly progressive one Course with an initially very flat rise on. According to the invention, the embedding now results of the energy absorption element 16 in the elastic sole layer 10 a resulting characteristic curve, and practically as the sum or overlay of the two drawn in Fig. 5 Characteristics.

5, the transition from the start section 34 to the second curve section 36 is approximately 1/3 of the maximum deformation path s _max and preferably a force F ₁ . The maximum deformation path s _max is approximately 10 to 20 mm, in particular 10 to 15 mm. The force F ₁ is in the range of approximately 3,000 to 4,000 N. The transition from the second curve section 36 to the end section 38 is then approximately 2/3 of the maximum deformation path s _max and preferably a force F ₂ which is in the range of approximately 1,000 to 3,000 N. The maximum deformation path s _max is preferably achieved at a force F ₃ of approximately 5,000 N.

The sum of the two curves in FIG. 5 results in a curve which increases relatively quickly to the maximum force F ₃ and also remains approximately constant at this value F ₃ over the further distance. This results in a very large area under the resulting curve, which corresponds to the energy consumption.

The deformation or suspension behavior of the energy absorption element 16 can be influenced in a wide range by design. According to FIGS. 4 and 4a, it is expedient if the flat-conical peripheral section 26 of the second wall 22 has a wall thickness that changes from the outer peripheral edge in the direction of the center, preferably increasing. 4a, the wall thickness in the region of the outer peripheral edge is denoted by d ₁ , while the wall thickness at the transition to the central section 28 is illustrated by d ₂ . The flat central section 28 is preferably formed with a wall thickness d ′ which corresponds approximately to the (larger) wall thickness d _{2 of} the peripheral section 26. The characteristic curve can be influenced effectively by these dimensional relationships in particular. For example, as an alternative to the course illustrated in FIG. 5, it can also be achieved that the second curve section 36 runs approximately linearly and approximately parallel to the path axis (abscissa). Furthermore, of course, a more clearly decreasing course can also be achieved.

1 to 3, the energy absorption element 16 is preferably seated directly on the steel midsole 12 expediently engages an extension 42 of the first wall 20 for relative position fixation in an opening in the midsole 12 a. This allows the steel midsole 12 simultaneously with the energy absorption element 16 in the Sole layer 10 are embedded, resulting in a simple Manufacturing leads.

The energy absorption element is located in its upper area 16 also directly in connection with the insole 14. The insole 14 covers the central one Center section 28 of the second wall 22 such that the Material of the elastic sole layer 10 - see Fig. 1 - only in the area of the flat-conical peripheral section 26 with wedge-like decreasing thickness radially from outside to inside between the energy absorption element 16 and the insole 14 is arranged. Thus the energy absorption element lies 16 with direct investment contact directly between the Steel midsole 12 and the insole 14. Therefore lies the foot - apart from the midsole 14 and one possibly additionally provided insole - directly on the energy absorption element 16. hereby is achieved in the event of an impact that almost immediately Characteristic curve of the energy absorption element 16 according to the invention comes into effect, especially in the initial area of the deformation path to achieve a high energy consumption.

Gesamthöhe H etwa 10 bis 20 mm;

Außen-Durchmesser ca. 60 bis 80 mm;

Durchmesser des Mittenabschnittes 28 etwa 15 bis 25 mm;

lichte Höhe des inneren Hohlraums 24 ca. 5 bis 12 mm;

Dicke der zweiten Wandung 22 im Bereich des konischen Umfangsabsschnittes ca. 2 bis 5 mm;

Dicke d' des Mittenabschnittes 28 ca. 3 bis 5 mm;

Konuswinkel α der flach-konischen Umfangswandung 26 etwa 120° bis 150° (gemäß Fig. 4 ca. 135° und gemäß Fig. 4a ca. 140°).

In order to achieve the described mode of operation, the energy absorption element 16 preferably has the following dimensions in a practically implemented embodiment:

Total height H about 10 to 20 mm;

Outer diameter approx. 60 to 80 mm;

Diameter of the central portion 28 about 15 to 25 mm;

clear height of the inner cavity 24 approx. 5 to 12 mm;

Thickness of the second wall 22 in the area of the conical circumferential section is approximately 2 to 5 mm;

Thickness d 'of the central section 28 approx. 3 to 5 mm;

Cone angle α of the flat-conical peripheral wall 26 approximately 120 ° to 150 ° (according to FIG. 4 approximately 135 ° and according to FIG. 4a approximately 140 °).

In addition to the dimensions, the characteristic of the Energy absorption element 15 of course also by the used Affect material. A sprayable is preferred thermoplastic with a hardness about Range from 60 to 70 Shore-D used. Suitable for this is for example polyamide (PA, e.g. PA6), polypropylene (PP) or polyoxymethylene (POM). The two can Individual parts (lower and upper wall 20, 22) also from different Materials exist.

The present invention leads - except for an improved one Energy consumption behavior - also at an inexpensive Manufacturability. For this purpose, it is particularly advantageous that the energy absorption element 16 is the same for all shoe sizes, i.e. with the same size, can be formed. hereby only a single set of molding tools is required. The handling when embedding the energy absorption element is very simple because of its preferred Connection with the steel midsole well fixed and very is positioned exactly.

In contrast to the embodiment according to FIG. 2, in which the energy absorption element 16 with the flat, first wall 20 rests on the steel midsole 12 is in the Embodiment according to FIG. 6 provides an inverted arrangement. This means that, according to FIG. 6, the energy absorption element 16 with the smaller central section 28 of the second wall 22 on the midsole 12 rests, while the flat, larger first area Wall 20 faces upwards. With this embodiment achieved better comfort because the foot has a larger area supported directly by the energy absorption element 16 becomes.

In the embodiment according to FIG. 7, the energy absorption element is located 16 immediately below a sole or footbed-like insert 44. This insert 44 expediently consists of a relatively dimensionally stable, but elastically deformable plastic material. In Fig. 7 an embodiment is shown in which the energy absorption element 16 with the central section 28 of the second Wall 22 abuts the underside of the insert part 44. Alternatively, however, is also of particular advantage a reverse arrangement of the energy absorption element 16 possible; a larger area of the first wall 20 on the insert part 44 in turn a better one Comfort achieved.

The invention is not limited to that shown and described Embodiments limited, but also includes all designs having the same effect in the sense of the invention. Furthermore, the invention is not yet based on the Claim 1 defined combination of features limited, but can also be by any other combination of certain characteristics of all of the individual characteristics disclosed be defined.

Claims (10)

1. A shoe base construction (4), in particular for safety shoes (1), having a sole structure (6) with an energy-absorbing element (16) which is arranged in the heel region for protecting against shock- or impact-induced injuries and has a flat, approximately discus-like hollow body (18) of circular contour with a first wall (20) and a second wall (22), the second wall (22) being of shell-like, in particular frustoconical design, the shell-like second wall (22) having a shallow-conical circumferential section (26) and a central, planar middle section (28) which is connected integrally to the circumferential section (26) and is approximately parallel to a foot-supporting surface defined in the heel region by the sole structure (6), and the two walls (20, 22) of the hollow body (18) being designed as separate mouldings and being connected tightly to one another in the region of their circumferential borders - preferably via a form-fitting or force-fitting snap-in connection (30) - such that the inner cavity (24) of the embedded hollow body (18), which is encapsulated in particular with PU, is free of the enclosing material of the elastic sole layer (10), characterized in that the first wall (20) is of planar design.
2. A shoe base construction according to claim 1, characterized in that the one wall (20) has an encircling border web (32), in which the other wall (22) engages in a latching manner.
3. A shoe base construction according to either of claims 1 and 2, characterized in that the shallow-conical circumferential section (26) has a wall thickness (d₁ to d₂) which changes, in particular increases, from the outer circumferential border towards the centre.
4. A shoe base construction according to any one of claims 1 to 3, characterized in that the planar middle section (28) has a wall thickness (d') which corresponds approximately to the wall thickness (d₂) of the circumferential section (26) at the transition to the middle section (28).
5. A shoe base construction according to any one of claims 1 to 4, characterized in that the energy-absorbing element (16) is seated directly on an intermediate steel sole (12) of the sole structure (6), to be precise in particular on the top side thereof, which is directed towards an inner sole (14) or insole, an extension (42) of the first wall (20) or of the second wall (22) preferably engaging in an opening of the intermediate sole (12) for fixing the relative positions.
6. A shoe base construction according to any one of claims 1 to 5, characterized in that, in its top region, the energy-absorbing element (16) is in direct contact with an inner sole (14) or a sole- or foot-bed-like insert part (44).
7. A shoe base construction according to claim 6, characterized in that the inner sole (14) or the insert part (44) covers over the central middle section (28) of the second wall (22) such that the material of the elastic sole layer (10) is arranged only in the region of the shallow-conical circumferential section (26) with the thickness decreasing in a wedge-like manner from the outside to the inside between the energy-absorbing element (16) and the inner sole (14) or the insert part (44).
8. A shoe base construction according to any one of claims 1 to 7, characterized in that the energy-absorbing element (16) consists of a thermoplastic material which can be injection-moulded and has a hardness approximately in the range of from 60 to 70 Shore D, for example of PA, PP and/or POM.
9. A shoe base construction according to any one of claims 6 to 8, characterized in that the energy-absorbing element (16) is arranged with the first, essentially planar wall (20) oriented upwards.
10. A shoe base construction according to any one of claims 6 to 8, characterized in that the energy-absorbing element (16) is arranged directly beneath the insert part (44) - which preferably consists of a relatively dimensionally stable plastic material - in particular the first wall (20), or else the second wall (22), being directed towards the insert part (44).

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