Shoe sole with improved shock absorbing effect

Field of the Invention

0001This Invention applies to semi-finished products and connected technologies used in the production of footwear; more precisely, this Invention describes the shoe lower portion in contact with the ground called sole, also called outer sole.

Background to the Invention

0002Footwear is a highly diversified leather goods item in terms of shape, use and declination. Today, there are thousands of models especially thanks to the use of new materials and new technologies in the production processes, which allow the consumer to have an extremely wide offer on the market.

0003It is possible to differentiate some general types of footwear, however said distinction has boundary lines whose tracing is increasingly difficult: <ol id="ol0001"><li>a. a footwear type is the classic footwear made of natural materials, which reproposes the stylistic figures of the past and is still made today with almost manual techniques, which give great value and exclusivity to the finished product,</li><li>b. another footwear type is the technical footwear, made specifically for sports activities, including competitive ones. These shoes have benefited from technological innovations resulting from the use of synthetic materials and advanced assembly processes, both focused on obtaining characteristics aimed at enhancing athletic performance and providing adequate protection to the foot. This category includes footwear for running, speed, tennis, trekking, up to specific products for sports such as cycling, motorcycling, skiing, climbing etc.</li><li>c. another footwear type is the one that combines some characteristics of the previous category, therefore the technical performance, with peculiarities of improved comfort, all combined with a style that always adheres to the dictates of current fashion. Those footwear have an informal and youthful appearance, with distinctive features given by a refined, unique appearance but which in some interpretations do not give up on reworking even the classic styles of the first category above indicated.</li></ol>

0004Footwear that can be classified in the third category above therefore has a design origin that always remains attentive to technical performance such as comfort, correct support for the foot during walking, a high breathability factor and gas exchange between the inside and outside, use of materials with antifungal and germicidal characteristics, improved flexibility, etc.

0005Footwear in the third category above, such as those intended for competitive use, mainly uses cutting-edge material technologies and construction processes that are optimized for large production quantities and, as already highlighted in paragraph 002, point c), can share some technical refinements deriving from competitive use for the benefit of the general user.

0006A shoe can be separated into some macro-parts, for example: <ol id="ol0002"><li>a. the upper (10) which covers and contains the foot in the upper and descending portions, which has an opening that can be opened and closed on the instep (11) and which allows it to be worn,</li><li>b. the sole (12) connected to the upper (13), which creates the external edge and the support of the foot of the shoe at the bottom. In its lower section, the surface of the sole comes into contact with the ground through the tread (14), that is a process or layer designed to improve grip and adherence.</li></ol>

0007There are further reinforcement and finishing elements such as the internal sole, to increase comfort, the linings coupled to the upper - also internal to the shoe - finishing welts etc.

0008It is obvious that the foot during walking releases variable forces in directions mostly orthogonal to the ground, so it is the sole that is most affected by all those technical improvements aimed at improving the pleasure or technical performance of walking.

0009In general, the soles thus constructed are mainly the result of manufacturing processes through injection and molding of synthetic materials, which can combine unique elasticity and resilience factors that cannot be reproduced with natural materials, such as leather and its derivatives.

0010Prior Art today offers a large differentiation of substances such as Polyurethane (PU), PVC, EVA (Ethylene Vinyl Acetate) etc. and each of them has peculiar mechanical characteristics. EVA, for example, is a cross-linkable polymer which, when subjected to an adequate temperature inside a mould, expands and produces an extremely light, flexible semi-finished product with no shape memory. While EVA is not easily recyclable, except in its inert filler added to another material, Thermoplastic Polyurethane can instead be reused through fusion and moulding, thus proving extremely advantageous.

0011The use of these materials, with the appropriate formulation variations to enhance some of their mechanical characteristics, is enhanced by the geometric shape of the sole and by the solutions that are designed inside it, thus creating a semi-finished product that allows combining both a peculiar aesthetic aspect and a series of characteristics that highlight its functionality.

0012Nike's patent <patcit id="pcit0001" dnum="US2022248804A1"><text>US2022248804A1</text></patcit> describes, for example, a sole in synthetic material in which a peculiar cushioning element, called a "barrier layer", is inserted and incorporated inside a closed volume, also filled with liquids or gases. This cushioning element is located in the central/front area of the sole and manages the pressure forces coming from the foot. The sole, constructed in this way, presents unquestionably great advantages but also a significant complexity in the construction process.

0013Patent <patcit id="pcit0002" dnum="WO2016191109A1"><text>WO2016191109A1</text></patcit> describes a sole in which an elastic layer is worked inside through openings created in various sizes and dimensions, in order to modify the elastic effect of the aforementioned layer. This is an interesting but extremely complicated solution, since synthetic soles are generally produced by injection and mould, thus forcing the inventive process within the technical limits of a layout that allows easy extraction of the sole from the mould.

0014Publication <patcit id="pcit0003" dnum="US2022378150A1"><text>US2022378150A1 by Nike</text></patcit> describes a sole in which the shock-absorbing element consists by a series of recesses and lobes facing each other that when in contact create a cushion effect. This layout includes closed chambers also filled with liquids; in this case, too, the layout described is very efficient but complicated to implement.

0015Reebok's patent <patcit id="pcit0004" dnum="US7966749B2"><text>US7966749B2</text></patcit> describes an element that can be inserted inside a sole, composed of two closed chambers connected by a corrugated channel. The presence of air inside the two chambers, air that can pass from the first chamber to the second and vice versa, creates a shock-absorbing element. Again, this is a highly efficient but extremely complicated system.

0016Adidas's patent <patcit id="pcit0005" dnum="US9930928B2"><text>US9930928B2</text></patcit> describes a sole that includes two regions of space in which two types of materials are used, a first type of expanded materials that are free to move, and a second region of more compact materials that penetrates the first region causing it to block, thus creating a controlled shock-absorbing effect. The described solution is once again extremely complex and limits the cost-effectiveness of the Invention.

0017Newton Running Company publication <patcit id="pcit0006" dnum="WO2023122761A1"><text>WO2023122761A1</text></patcit> describes a sole in which there are two layers facing each other. The two layers are worked using sinusoidal undulations and are coupled by the interposition of a membrane. The presence of a compressive force causes the two layers to penetrate and the membrane creates a progressive resistance, storing the energy that will be released to the foot as a rebound force, opposed to the compression force. This solution is highly functional but has construction complications and economic inefficiency.

0018Mizuno's publication <patcit id="pcit0007" dnum="US2020305541A1"><text>US2020305541A1</text></patcit> describes a sole made up of different layers, therefore different coupled soles. A first sole has a plurality of protrusions on the side in contact with the foot, the outer sole has a plurality of protrusions on the surface in contact with the ground, and an intermediate sole between the two has a great rigidity. The combination of the protrusions between the layers of the different soles creates a shock-absorbing effect. This solution, however, is complex and furthermore is proven to create a floating effect during walking that is not always pleasant, and for this reason this solution can be improved.

0019New Balance Patent <patcit id="pcit0008" dnum="US6026593A"><text>US6026593</text></patcit> describes a shock-absorbing element designed to be inserted into the sole of a shoe. The shock-absorbing element consists of several closed tubular elements. This solution can trigger an evident floating effect and presents a certain structural complexity.

0020The aim of this Invention is to overcome the criticality in the Prior Art to create a sole for shoes made of synthetic materials in which: <ol id="ol0003"><li>a. the sole must be produced by injection and mould, therefore it must not have a layout that would prevent its extraction from the aforementioned mould, or a layout that would make the aforementioned operation particularly difficult,</li><li>b. the sole must consist of a minimum number of overlapping layers, preferably a single layer, in order to reduce production costs,</li><li>c. the sole must contain a small number of semi-finished products inside it, semi-finished products whose purpose is also to absorb the shocks due to walking,</li><li>d. the sole must also be manufactured with synthetic materials of different origins but in such a way as to keep its comfort characteristics intact,</li><li>e. the sole must have a peculiar shock-absorbing and rebound characteristic while avoiding the floating effect, said effect due to a linear capacity to absorb the forces that arise during walking,</li><li>f. the sole must be particularly light, in order to be able to assemble footwear that is comfortable to use.</li></ol>

Summary of the Invention

0021The Invention describes a shoe sole featuring a non-linear shock-absorbing feature and a unique rebound effect, favoring a layout designed for weight maximum containment and maximum ease of use.

Benefits of the Invention

0022This Invention offers the following advantages: <ol id="ol0004"><li>a. unlike many other cushioning and rebound systems integrated into a shoe sole, the Invention - i.e. the sole - allows for the creation of a non-linear elastic characteristic, which regresses as the foot pushes,</li><li>b. unlike many other cushioning and rebound systems integrated into a shoe sole, the shock-absorbing function is proposed with different degrees of intensity in specific area of the surface of the Invention, without resorting to excessive technical complications,</li><li>c. unlike many other cushioning and rebound systems integrated into a shoe sole, the technical elements that allow for the improvement of the rebound effect in the Invention have a small surface and a limited mass,</li><li>d. the Invention - i.e. the sole - can be produced also without the technical elements that improve the rebound effect without losing its non-linear shock-absorbing characteristic,</li><li>e. when the technical elements that improve the rebound effect are placed in the Invention, no additional work is necessary for their positioning on the sole,</li><li>f. the Invention - i.e. the sole - can be made with a single synthetic material worked to obtain different characteristics of elasticity and rebound.</li></ol>

Description of Diagrams

0023A table with diagrams is included with the documentation for this application to illustrate the characteristics of the invention, with application variations highlighted where described. More specifically it includes: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001"><b>Fig.1</b></figref> [<figref idref="f0001">fig.1</figref>] showing a sole for footwear combined with an upper in the Prior Art,</li><li><figref idref="f0002"><b>Fig.1a</b></figref> [<figref idref="f0002">fig.1a</figref>] showing a top view and a sectional view of the sole as per this Invention,</li><li><figref idref="f0003"><b>Fig.1b</b></figref> [<figref idref="f0003">fig.1b</figref>] showing a further embodiment of the central area of the sole according to the idea of this Invention,</li><li><figref idref="f0004"><b>Fig.2</b></figref> [<figref idref="f0004">fig.2</figref>] showing a top view of the sole as per the Invention in which the perimeter cracking and the transverse cracking are visible,</li><li><figref idref="f0005"><b>Fig.2a</b></figref> [<figref idref="f0005">fig.2a</figref>] showing a further embodiment of the perimeter cracking according to the idea of the Invention,</li><li><figref idref="f0005"><b>Fig.3</b></figref> [<figref idref="f0005">fig.3</figref>] showing the movement of the sole central area as per the Invention, when subjected to the forces resulting from walking,</li><li><figref idref="f0006"><b>Fig.4</b></figref> [<figref idref="f0006">fig.4</figref>] showing the non-linear characteristic of the increased elasticity factor as per this Invention,</li><li><figref idref="f0006"><b>Fig.5</b></figref> [<figref idref="f0006">fig.5</figref>] showing a longitudinal section of the sole as per the Invention,</li><li><figref idref="f0007"><b>Fig.6</b></figref> [<figref idref="f0007">fig.6</figref>] showing a transversal section of the sole as per the Invention with an additional element applied to improve the rebound effect,</li><li><figref idref="f0008"><b>Fig.7</b></figref> [<figref idref="f0008">fig.7</figref>] showing a top view of the sole as per the Invention in which the elements of improvement of the rebound effect are evident,</li><li><figref idref="f0009"><b>Fig.7a</b></figref> [<figref idref="f0009">fig.7a</figref>] showing a top view of the of the sole in a further embodiment of the idea of the Invention in which the elements of improvement of the rebound effect are evident,</li><li><figref idref="f0010"><b>Fig.8</b></figref> [<figref idref="f0010">fig.8</figref>] showing a cross-section of the sole as per the Invention where the cracks are partially filled with an elastomeric polymer according to the idea of the Invention,</li><li><figref idref="f0011"><b>Fig.9</b></figref> [<figref idref="f0011">fig.9</figref>] showing a lateral section view of the sole as per the Invention during the walking phase,</li><li><figref idref="f0012"><b>Fig.10</b></figref> [<figref idref="f0012">fig.10</figref>] showing a top view of the sole as per the Invention with an elastic buffer element inserted,</li><li><figref idref="f0013"><b>Fig.11</b></figref> [<figref idref="f0013">fig.11</figref>] showing a detail of the height of an elastic buffer element.</li></ul>

Description of the Invention

0024The description of the various methods for implementing this Invention is outlined for illustration purposes, therefore all possible modifications of an obvious nature in its field of application, when carried out by industry operators, will not limit the terms for protecting the patent itself.

0025The device described in this Invention is related to further solutions already known in the Prior Art which are used for the correct implementation in the chosen technical field.

0026In this text, the reference to a single technical element can also refer to a plurality of the same within the scope of the Invention, unless specifically indicated.

0027In the present text, the term "Sole" refers to the improved sole.

0028According to the embodiment of the Invention, is designed a sole for footwear in synthetic material, obtained by the already known injection processes on a mould. The Sole can also be made by a casting technique on a mould, when deemed feasible and consistent with additional factors, even of a non-technological nature.

0029According to the embodiment of the Invention, the synthetic material that constitutes the sole can be chosen from those already known in the State of the Art, for example EVA (Ethylene Vinyl Acetate), Polyurethane (PU), TR etc.: the choice will depend on the quantity of the desired shock-absorbing effect, an effect that will then be modulated by the peculiar shape of the sole as disclosed in this text.

0030According to the embodiment of the Invention, the specific processes that provide the Sole with an improved shock-absorbing effect and an improved "rebound" effect - i.e. a rebound effect - are applicable to any sole produced by injection/mould or casting/mould; for this reason, in the drawing table, the aesthetics of the sole shown therein can conveniently be modified according to production needs.

0031According to the embodiment of the Invention, the Sole presents a differentiation of its structure in the central area (10a) compared to the peripheral area (11a). <figref idref="f0002">Fig.1a</figref> shows how the cross-section profile of the sole (Z-Z') equipped with its tread (15a) which rises peripherally with a wall along a vertical axis (14a) up to its upper outer edge (12a) to descend again (13a) until it meets a central area (10a). The central area of the sole is the one that is most subjected to the downward thrust given by the foot, and is the one involved in producing the shock-absorbing functions during walking.

0032According to the embodiment of the Invention, the central area of the sole is equipped with an intrinsic elasticity characteristic deriving from the materials of which the Sole is made, as described in paragraph 0044. In the Prior Art, however, the use of elastic materials for the manufacturing of footwear soles can create an unwanted phenomenon during walking, namely a floating effect that makes the sensation of the positioning of the foot on the ground uncertain.

0033The said floating effect, if can be sought to increase the degree of comfort of the shoe, namely the ability to absorb shocks during walking, however it does not make it possible to perceive the ground as a stable reference on which to operate the necessary thrusts and movements of the foot for walking, running or practicing sports.

0034The floating effect can therefore create disorientation, precarious balance; in general it occurs on all those footwear equipped with a high shock-absorbing effect of the sole.

0035In the Prior Art it is known that the forces acting from the foot towards the sole during walking are distributed differently on the various areas of the same sole: in particular the heel (18a) and the tip of the foot (17a) are the areas of pressure of the support and thrust forces, which in rapid alternation allow walking.

0036Furthermore, during the support of the heel, the area subjected to a thrust towards the ground is smaller than the area that is created when the foot is parallel to the ground, so the deformation that the sole undergoes is decidedly higher. The same reasoning can be applied to the thrust that the forefoot generates during walking towards the sole in its apical part.

0037Since these movements generate great forces and thrusts on small surface areas of the sole, namely the apical area of the sole (17a) and the posterior area of the heel (18a), the final result is a greater tendency for the floating effect to arise.

0038In order to contain and control the floating effect, and according to the embodiment of the Invention, a continuous perimetral crack is appropriately designed on the internal perimeter of the sole (16a) whose effect is to separate the central area thus formed (10a) from the peripheral area (12a, 13a, 14a), i.e. the area composed of the elevation of the tread along the vertical axis, its edge and the descending profile, keeping the two areas mutually united thanks to the lower portion of the sole, i.e. that of the tread (15a).

0039According to a further embodiment of the Invention, the central area of the sole (10b) can conveniently be added in a subsequent processing phase to the tread area (11b) as disclosed in <figref idref="f0003">Fig.1b</figref>, while respecting the construction criteria of the present Invention as declared in 0051, i.e. the central area of the sole is separated from the peripheral area (12b, 13b, 14b) by the presence of the perimetral cracking.

0040According to the embodiment of the Invention, the creation of a central area of the sole not in contact with the edge of the same amplifies the effect of softness and elasticity during walking, as the yielding of this area of the sole is enhanced by its own deformation, a deformation that develops freely along the empty space created by the perimetral cracking.

0041According to the embodiment of the Invention, the elasticity characteristic is defined as "enhanced" and has not a linear character, since once the area of the perimetral crack (30) has been filled by the application of the vertical forces that develop during walking (33), the material forming part of the central area of the sole comes into contact with the edge of the sole (31,32) which stops its expansion and deprives the sole of the floating effect, limiting its elasticity, triggering a non-linear damping phenomenon.

0042According to the embodiment of the Invention, what is created is: <ol id="ol0005"><li>a. firstly a characteristic of enhanced elasticity during walking generated by the central area of the sole free to expand laterally in the perimetral cracking,</li><li>b. secondly a stoppage of the shock-absorbing effect that interrupt it of its linear progression (40), that is a non-linear damping effect.</li></ol>

0043According to the embodiment of the Invention, the non-linearity of the enhanced elasticity factor depends on the width of the perimeter crack, however - as disclosed in paragraphs 0050, 0051 and 0052 - the progression of the thrust forces generated by walking and the areas subjected to such stresses are not constant; for this reason, the perimetral crack of the sole will also be advantageously designed with variable widths depending on its development along the internal perimeter of the sole.

0044According to a further embodiment of the Invention, and by virtue of further technical characteristics that will be disclosed in the continuation of this Description, it is also possible to provide a layout of the crack with constant width along the entire internal perimeter of the sole. This will also depend on the technical elasticity performances required during the design phase of the Sole, on the materials used and on further construction factors.

0045Having <figref idref="f0004">Fig.2</figref> as a reference, the following areas of the sole (20) are identified in the present exposition: <ol id="ol0006"><li>a. an apical area (21) that goes from the front vertex of the sole to the section line A-A',</li><li>b. an area of the forefoot that goes from the section line A-A' of the sole to the section line B-B',</li><li>c. an intermediate front area that goes from the section line B-B' to the section line C-C' (22),</li><li>d. a central area that goes from the section line C-C' to the section line D-D' (23),</li><li>e. an intermediate rear area that goes from the section line D-D' to the section line E-E' (24),</li><li>f. a rear area (25), also called the heel area, that goes from the section line E-E' to the rear vertex of the sole.</li></ol>

0046According to the embodiment of the Invention, for each area of the sole the perimetral cracking assumes a variable value depending on the fact that the increased elasticity must be contrasted more or less by the damping factor, depending on the thrusts that arise during walking; an example of variable thickness of the perimeter cracking is provided here: <ol id="ol0007"><li>a. the apical area is subjected to great stress and must provide an excellent sensation of support and precision in the push of the foot, for which the damping element of the enhanced elasticity is made to act rapidly - in order to limit the floating effect - by means of a perimetral cracking with a width limited to 3 mm (201a),</li><li>b. the forefoot area of the sole is designed with an enhanced elasticity factor higher than the one in the apical area, so that the width of the perimetral cracking increases - along the portion of the area delimited by the section lines A-A'/B-B' - from 3 mm to 4 mm (26),</li><li>c. the intermediate front area is designed with an enhanced elasticity factor higher than the one in the forefoot area, so that the width of the perimetral cracking increases - along the portion of the area delimited by the section lines B-B'/C-C' - from 4 mm to 5 mm (27),</li><li>d. the central area is designed with an enhanced elasticity factor higher than the one in the intermediate front area, so that the width of the perimetral cracking increases - along the portion of the area delimited by the section lines C-C'/D-D' - from 5 mm to 6 mm (270),</li><li>e. the intermediate rear area is designed with an enhanced elasticity factor lower than the one in the central area of the sole, so that the width of the perimetral cracking decreases - along the portion of the area delimited by the section lines D-D'/E-E' - from 6 mm to 3 mm (271),</li><li>f. the heel area must provide a good support, so the damping element of the enhanced elasticity is made to act quickly - in order to limit the floating effect <ul id="ul0002" list-style="dash" compact="compact"><li>by means of a perimetral cracking with a width limited to 3 mm (272), similarly to the apical area.</li></ul></li></ol>

0047According to the embodiment of the Invention, what is created - thanks to the perimetral cracking with variable thickness - is a damping factor of the elastic enhanced element compared to a Prior Art sole, factor weighted by the forces that insist on it and by the areas involved in walking. The enhanced elasticity factor therefore loses its linear characteristic, i.e. the proportionality with the force, as it is dampened by the contact between the edges of the central area of the Sole (10a) and the perimetral areas of the Sole (12a, 13a, 14a).

0048According to a further embodiment of the Invention, it is possible to implement a net variation in the width of the perimetral cracking instead of the progressive variation, as revealed in paragraph 0059 and in <figref idref="f0004">Fig.2</figref>. By observing the detail of <figref idref="f0005">Fig. 2a</figref>, section B (taken as an example), the variation in the width of the perimetral cracking from the previous level (21c) to the next level (22c) is achieved by a sudden increase in the aforementioned level (20c) or by means of a step, without thereby taking away any of the advantages of the Invention as revealed in the previous paragraphs. What is therefore obtained is that the width of the perimetral cracking within the limits of each individual area of sections A/A', B/B', C/C', D/D', E/E' remains constant.

0049According to the embodiment of the Invention, and in order to further vary the elasticity deriving from the material used for the production of the sole, the central area of the sole (10a) can be further processed by creating transverse slots, of variable section and variable length. <figref idref="f0004">Fig.2</figref> shows an example of the quantities of the groups of slots that can be made in the central area of the sole, namely: <ol id="ol0008"><li>a. a first group of three cracks (28, 29, 20a) that goes from the forefoot area to the intermediate front area, with a thickness of 2 mm,</li><li>b. a second group of three cracks (21a, 22a, 23a) that goes from the intermediate front area to the central area, with a thickness of 4 mm,</li><li>c. a third group of three cracks (24a, 25a, 26a) that goes from the central area to the intermediate rear area, with a thickness of 4 mm excluding the crack located in the central area of the sole (24a) which has a thickness of 6 mm,</li><li>d. a fourth group of three cracks (27a, 28a, 29a) that goes from the intermediate rear area to the heel area, with a thickness of 2 mm.</li></ol>

0050According to the embodiment of the Invention, the slot groups allow to adapt the variety of material used for the construction of the sole to the various applications in the types of footwear. In fact it is possible to increase the degree of the enhanced elasticity of the material of which the sole is made by making the slots disclosed in paragraph 0062, while maintaining a high damping factor resulting from the contact of the internal area of the sole with the respective edge.

0051<figref idref="f0006">Fig.5</figref> shows a longitudinal section of the Sole with an example of the cracking groups (50) described in paragraph 0062.

0052As described in this text, the Sole is preferably constructed by injecting synthetic materials into moulds, more precisely by injection or even casting. It is well known that the production of moulds is very expensive, so a shoe soles manufacturing company is interested in optimising the production processes also with regards the economic parameters; it is therefore obvious that using a single material is more economically advantageous. The Sole according to the idea of the Invention can be produced, with the same material used, with different elasticity characteristics and different damping characteristics, thanks to the perimetral cracking and the transversal cracking groups in the central area of the sole. Furthermore, as regards the presence of transverse crack groups in the central area of the sole, it is also possible to implement single cracks, or even in some cases a single crack forming part of a single group, appropriately positioned.

0053According to a further embodiment of the Invention, a technology is devised that, applied to the Sole, allows to modify the "rebound" characteristics, i.e. the rebound of the elastic element inherent in the material used for the construction of the sole, but also to modify the overall behaviour of the sole when used for walking, running, jumping, etc.

0054The developed technology avoids to produce "n" moulds for "n" elasticity and rebound characteristics, but to adapt a limited number of models of the Sole - models differentiated by quantity of crack groups or width of perimetral cracking - to additional characteristics. Furthermore, this technique according to the idea of the Invention allows to reduce the variety of synthetic materials used for the creation of the Sole, as it is possible to limit or increase the elasticity and rebound characteristics of a single material.

0055According to what has already been described in the text of the present invention, the technical characteristics of the sole that affect the performance offered during its use are: <ol id="ol0009"><li>a. the material of which the sole is made,</li><li>b. the degree of perimetral cracking as per this invention,</li><li>c. the quantity and dimensions of the transverse cracking groups in the central area of the sole as per this invention.</li></ol>

0056According to a further embodiment of the invention, two further factors are added to the above-mentioned factors, namely: <ol id="ol0010"><li>a. the insertion of additional elastic devices in the sole,</li><li>b. the partial or complete filling of the cracks, both the perimetral cracking and those of the individuated groups, with polymers that harden when subjected to mechanical stress.</li></ol>

0057According to a further embodiment of the Invention, is designed an elastic device in metal, for example in harmonic steel, or synthetic material without shape memory, for example carbon or composite material, and said elastic device is inserted into the spaces created by the perimetral cracking as per this Invention.

0058According to a further embodiment of the Invention, the elastic device (64) has a "C" shape, or the shape of a staple, as can be seen from the cross-section of the sole in <figref idref="f0007">Fig.6</figref> (60) in which the vertices of the sections folded at 90° (61) of the elastic device have a further 180° torsion to form a hook (62) such as to cause a thickening of the apical section. The dimensions of the elastic devices allow them to be inserted into the internal edges of the perimetral crack in a transverse position, so as to overlap the central part of the sole (63) and therefore create an additional support surface for the foot, a surface which will react to the vertical forces generated by walking, with a rebound effect enhanced by the presence of the elastic devices.

0059According to a further embodiment of the Invention, the quantity of elastic devices that can be inserted on the sole depends on the quantity of rebound that one wishes to obtain; the elastic devices are in fact designed with no mechanical memory, so that once subjected to vertical forces coming from walking, they flex and react with an upward thrust, which is added to that of the material of which the Sole is made.

0060According to a further embodiment of the Invention, the hook in the apical area of the 90° folded section of the elastic device fits tightly into the perimetral cracking, allowing its stability in contact with the sole during the construction phases of the sole itself.

0061According to a further embodiment of the Invention, the elastic devices do not influence the non-linear damping factor of the enhanced elasticity of the sole, since they limit the volume of the perimeter crack in a negligible way; surprisingly, however, they increase said characteristics since the aforementioned devices have limited bending capacity along the area of the section bent at 90°, or they bring higher rigidity to the material in the section of the sole external to the perimetral cracking.

0062<b>In</b> the top view of <figref idref="f0008">Fig.7</figref>, there are a series of four elastic devices (70,71,72,73) inserted in the sole (74), appropriately distributed between the apical area and the heel of the Sole.

0063According to a further embodiment of the Invention, the elastic devices inserted in the sole to improve the rebound effect, or the bounce, can highlight the section that rests on the horizontal surface of the central area of the sole - the one delimited by the perimeter crack - with appropriate different shapes, deriving from the need to increase or decrease the rebound effect. For example, it is possible to create asymmetric shapes (70a, 71a) to vary the performance by virtue of the internal area of the sole (73a) or the external area (74a), or vary its shape (72a) by creating support areas with heterogeneous surfaces, which interact with the rebound function.

0064According to a further embodiment of the Invention, both the perimetral cracking and those in groups in the central area of the sole provide a well-defined internal volume that can be filled, totally or partially, with dilating elastomeric polymers or with a material which tends to be fluid and in which the speed of the applied forces immediately stiffens the structure, changing its fluid state into a solid/semi-solid state.

0065These substances, already known in the State of the Art, if stressed with progressive forces diluted over time, tend to remain soft and/or fluid, therefore not modifying the behaviour of the structure that contains them. If, however, they are stressed suddenly, in a very short period, they stiffen, providing characteristics of protection, blocking, structure etc.

0066According to a further embodiment of the Invention, it is possible to fill one or more crack areas of the Sole (80,81) - both the perimeter ones and those of the groups inside the central area of the sole - with the aforementioned elastomeric polymers, which will react to the high and sudden thrust forces of walking - or running - in a manner proportional to the speed of the same, stiffening the structure of the sole in the chosen areas, or modifying the characteristics of elasticity and the floating effect. If, however, the walking forces are of lesser intensity and more distributed over time, for example in case of repeated slow walks, the structural and stiffening effects of the elastomeric polymer will be minimal.

0067Surprisingly, the presence of transverse crack groups can be used to provide additional technical performance to the sole thanks to the provision of a device designed to be inserted inside them. Until now, in fact, all the solutions described in this Description have focused on the rebound effect and on the enhanced elasticity characteristic, aspects that concern forces that are discharged vertically with respect to the ground.

0068According to a further embodiment of the Invention, therefore, it is also possible to modulate the propensity of the sole to bend more or less easily in a transverse direction (90), or to make its bending capacity depending on a more or less accentuated walking movement, therefore rendering said bending capacity programmable.

0069According to a further embodiment of the Invention, this is possible thanks to the design of an elastic buffer element without shape memory (100) constructed from a sheet of synthetic or metallic material, in the shape of a double ogive with two concave and opposite lateral walls (101,102) generating an internal opening (103). In the presence of compressive forces orthogonal to the two facing walls (104) the elastic buffer element has the capacity to compress (105) and therefore to exert a contrary repulsive force (106).

0070According to a further embodiment of the Invention, the elastic buffer elements are inserted inside one or more slots of the transverse slot group in such a way as to present their lateral walls in contact with the lateral walls of the slots (112). The elastic buffer elements are subjected to a cyclic compression generated by the walking movement, as the transverse slot groups will tend to cyclically close and open (91) due to the flexion of the sole. The forces that will be discharged on the elastic buffer elements will therefore be more or less contrasted by them.

0071According to a further embodiment of the Invention, furthermore, at the moment in which the sole no longer comes into cyclical contact with the ground, it will be conditioned by the thrust of the elastic buffer elements, a thrust which will facilitate the sole to stretch along the longitudinal axis.

0072According to a further embodiment of the Invention, it is also possible - when required - to make the elastic buffer elements with an adequate height "h" (110), or a height less than the depth "h1" (111) of the cracks of the transversal cracking group of the sole, in order not to compromise the compression of the aforementioned area during walking.

0073From what has been described above, therefore, and according to the embodiments of the Invention, the technical characteristics of the sole that affect the performance offered during their use depend on a comprehensive set of factors, namely: <ol id="ol0011"><li>a. the material of which the sole is made,</li><li>b. the perimetral cracking resulting as per this Invention,</li><li>c. the quantity and dimensions of the transverse cracking groups in the central area of the sole as per this Invention,</li><li>d. the insertion in the sole of one or more elastic devices as per this Invention,</li><li>e. the filling of the transverse cracking groups and the perimeter cracking as per this Invention with an elastomeric polymer,</li><li>f. the insertion inside the transverse cracking groups of one or more elastic buffer elements.</li></ol>

Invention examples

0074None.

Industrial Applications of the Invention

0075This Invention is applicable in any type of footwear, even in models not designed for a specific and highly specialized sporting activity, for the manufacturing of synthetic soles with improved comfort characteristics.

Citations in the Invention

0076Citation List follows: none.

Patent Literature

0077<ul id="ul0003" list-style="none"><li>PTL1: <patcit id="pcit0009" dnum="US2022248804A1"><text>US2022248804A1</text></patcit></li><li>PTL2: <patcit id="pcit0010" dnum="WO2016191109A1"><text>WO2016191109A1</text></patcit></li><li>PTL3: <patcit id="pcit0011" dnum="US7966749B2"><text>US7966749B2</text></patcit></li><li>PLT4: <patcit id="pcit0012" dnum="US9930928B2"><text>US9930928B2</text></patcit></li><li>PLT5: <patcit id="pcit0013" dnum="WO2023122761A1"><text>WO2023122761A1</text></patcit></li><li>PLT6: <patcit id="pcit0014" dnum="US2020305541A1"><text>US2020305541A1</text></patcit></li><li>PLT7: <patcit id="pcit0015" dnum="US6026593A"><text>US6026593</text></patcit></li></ul>

Non-Patent Literature

0078NPL1: none.