Method for manufacturing a midsole and shoe sole comprising such a midsole

Abstract

The invention proposes a method (300) for manufacturing a midsole (16) for a sole (14) of a shoe (10) with two portions each made of a cellular polymer material, characterized in that it comprises forming the second portion (22) of the intermediate sole (16), around an insert (20) forming a first portion, by means of an injection / foaming moulding method using supercritical fluid, and a sole produced by such a method in which the density of the second portion is higher than that of the first portion.

Description

Method of manufacturing a midsole and shoe sole comprising such a midsole Technical Field

[0001] The invention relates to the field of footwear, in particular sports footwear. More particularly, the invention relates to a stiffening reinforcement for a shoe sole, in particular for a sports shoe sole. Technical background

[0002] In the field of sports shoes, and particularly in the field of running shoes, the shoe must meet multiple performance criteria, including providing good cushioning to limit the risk of injury, while losing as little energy as possible from the runner and being as light as possible. To reconcile all these criteria, it is necessary to design sports shoe soles in several parts. The sole thus generally includes a midsole made of cushioning material, generally made of cellular polymer material which is sometimes even made of several portions having different properties. The sole of the shoe generally includes, on the underside of the midsole, an external sole, sometimes called a wear sole, which is intended to come into contact with the ground when using shoes.

[0003] It is thus known to produce an intermediate sole comprising a first portion made of a first cellular polymer material and having a first density, and comprising a second portion made of cellular polymer material and having a second density greater than the first density.

[0004] Document US2023150221 describes a method for manufacturing a midsole for a sports shoe which provides for manufacturing a first midsole portion, then a second midsole portion which is overmolded around the first portion. This assembly is then subjected to a supercritical fluid foaming process in an autoclave to obtain the midsole. Documents US2022225729 and US2022125158 describe sports shoe soles whose midsole comprises at least one portion made of a cellular material using a supercritical fluid.

[0005] The midsole portions made of cellular material using a supercritical fluid provide rebound characteristics, and therefore elasticity, which are particularly favorable for good energy restitution during the stride. However, to maximize rebound, the volume of the midsoles, particularly their thickness in the vertical direction, must be increased. To avoid excessively penalizing the weight of the sole, it is therefore necessary to use increasingly lighter cellular materials. These increasingly lighter materials can, however, have unfavorable characteristics, particularly in terms of tear resistance. This low tear resistance harms the durability of the midsole, from two angles: from the angle of intrinsic resistance to external "aggressions", such as cuts due to contact with hard objects (stones, etc.)), but also from the angle of the resistance of the assemblies with the other elements of the sole and / or the shoe.

[0006] In a classic construction, the different parts of the sole are assembled to each other by gluing and the upper of the shoe is assembled on the upper face of the midsole, for example by means of a mounting insole. These gluing operations can be complex and expensive and impose constraints in the design of the different parts to be able to ensure their assembly.

[0007] In the case of particularly light cellular materials, we can then end up with assemblies by bonding where the strength of the bonding itself is greater than that of one of the materials being assembled.

[0008] According to another aspect, in sports shoes in which the aim is to maximize the athlete's performance, provision is sometimes made to provide the sole of the shoe with an elastic stiffening reinforcement which, while allowing the sole to flex in the metatarsal area, is capable of storing energy in this flexion stage to restore it at the end of the stride, during the propulsive phase. Generally, stiffening reinforcements for sports shoes are made in the form of a thin plate, which substantially has the geometry of the sole, and which is most often attached between two portions of the midsole.

[0009] The aim of the invention is to propose a method for manufacturing an intermediate sole which makes it possible to obtain a sole meeting multiple performance criteria, including for example those of cushioning, energy restitution and weight. Statement of the invention

[0010] According to one aspect, the invention relates to a method of manufacturing a midsole for a shoe sole, in particular for a sports shoe, the midsole comprising a first portion made of a first cellular polymer material, comprising a stiffening reinforcement, and comprising a second portion made of a second cellular polymer material.

[0011] According to the invention, the method comprises the steps of: - manufacturing an insert comprising the first cellular polymer material; - placement of the insert in an injection mold having the shape of the midsole; - formation, around the insert, of the second portion of the midsole made of cellular polymer material by a supercritical fluid injection / foaming molding process.

[0012] The manufacture of the second midsole portion made of cellular polymer material by a supercritical fluid injection molding / foaming process makes it possible to obtain a cellular material with good elasticity and to obtain a second midsole portion having a relatively low density while ensuring reliable assembly of the two midsole portions, this assembly being obtained with a reduced number of operations.

[0013] Other features of such a method may include at least one of the following optional features, taken individually or in combination.

[0014] In some embodiments, the step of forming the second midsole portion may comprise a prior step of mixing the second polymer with the supercritical fluid, then injecting, into the injection mold, the mixture of the second polymer with the supercritical fluid. This method thus allows for optimal mixing. of the second polymer with the supercritical fluid, favorable to obtaining the second cellular polymer material particularly homogeneous in the extent of the second portion of the intermediate sole.

[0015] In some embodiments, the step of manufacturing the insert comprising the first cellular polymer material may for example be carried out by foaming with supercritical fluid in an autoclave comprising the formation of a primary blank with the first polymer material, placing the primary blank in an autoclave, injecting a supercritical fluid into the autoclave and infusing the supercritical fluid into the primary blank within the autoclave, depressurizing the autoclave transforming the primary blank into an expanded secondary blank. Manufacturing the insert forming the first midsole portion from cellular polymer material by such a method makes it possible to obtain a cellular material with good elasticity and to obtain a first midsole portion having an extremely low density.The possible weakness of certain characteristics of the material obtained, in particular in terms of tear resistance, is counterbalanced by the formation, around the insert, of the second portion of the midsole made of cellular polymer material by a supercritical fluid injection / foaming process, which makes it possible to obtain a material having better characteristics on this point. In such an embodiment, the step of manufacturing the insert may comprise a step of shaping the insert from the secondary blank, for example by compression molding, to obtain the insert, in particular in order to better control the shape of the insert.

[0016] In some embodiments, the assembly of the midsole can be obtained without added adhesive by at least partially embedding the first portion in the second portion. The absence of adhesive makes it possible to reduce the number of operations for carrying out the assembly and makes it easier to recycle the midsole.

[0017] The first portion of the midsole has a first density, and the second portion of the midsole has a second density which, in certain embodiments, may be greater than the first density. It is thus possible to have a first portion of the midsole that is extremely light, but with good elasticity and therefore energy restitution properties, and a second portion that is capable of absorbing the stresses experienced by the midsole while guaranteeing sufficient longevity of the sole.

[0018] In some embodiments, the step of placing the insert in an injection mold also includes placing at least one outsole component, and the at least one outsole component is assembled to the midsole by forming the second portion by injection molding / supercritical fluid foaming. This provides a reliable assembly of the two midsole portions and the at least one outsole component, this assembly being achieved with a reduced number of operations.

[0019] In some embodiments, the first polymer material comprises a polyether block amide, and / or the second polymer material comprises a polyether block amide. Such materials make it possible to obtain cellular materials having an excellent compromise between high elasticity and low density.

[0020] In some embodiments, the method also comprises, before the step of forming the second midsole portion, a step of supplying a stiffening reinforcement, the step of placing the insert in the injection mold also includes the placement of the stiffening reinforcement in the injection mold, and the step of forming the second portion of the midsole includes the formation, around the insert and the stiffening reinforcement, of the second portion of the midsole made of cellular polymer material by the injection molding / supercritical fluid foaming process. By integrating a stiffening reinforcement of the sole, it will be possible to obtain a sole with excellent energy restitution capacity and with good control of the deformation of the sole during the rolling of the foot, the sole thus best accompanying the rolling of the user's foot.By overmolding the second midsole portion made of cellular polymer material by the supercritical fluid injection / foaming process around the insert and the stiffening reinforcement, a reliable assembly of the two midsole portions and the stiffening reinforcement is obtained, this assembly being obtained with a reduced number of operations.

[0021] In certain embodiments comprising a stiffening reinforcement, the stiffening reinforcement is made of a composite material comprising reinforcing fibers embedded in a polymer resin. This makes it possible to obtain a stiffening reinforcement having an excellent compromise between, on the one hand, optimized stiffness and elasticity to ensure the stability of the sole during foot roll and to obtain excellent energy restitution at the end of foot roll, and on the other hand, weight and size as reduced as possible.

[0022] In some embodiments comprising a stiffening reinforcement, the stiffening reinforcement comprises an elongated profile, the profile having a curved guideline which is curved to follow a stiffening reinforcement geometry. The use of such a reinforcement makes it possible, for minimal weight, to optimally distribute the stiffness provided by the stiffening reinforcement along the length of the sole, for example from the heel area to the metatarsal flexion zone, or even in front of it.

[0023] In certain embodiments comprising a stiffening reinforcement, the assembly of the midsole is obtained without added adhesive, by at least partial embedding of the first portion and the stiffening reinforcement in the second portion. The absence of adhesive makes it possible to reduce the number of operations for producing an assembly, which by at least partial embedding of the first portion and the stiffening reinforcement in the second portion, is a reliable assembly of the midsole, in particular of the stiffening reinforcement, despite the large difference between the mechanical properties, in particular stiffness, between on the one hand the stiffening reinforcement, and on the other hand the cellular polymer materials of the insert and of the second portion of the midsole.

[0024] In certain embodiments comprising a stiffening reinforcement, the insert comprises a recess whose geometry is complementary to a corresponding part of the stiffening reinforcement, and, when placing the insert and the stiffening reinforcement in the injection mold having the shape of the midsole, the corresponding part of the stiffening reinforcement is placed in the recess of the insert to ensure the relative positioning of the insert and the stiffening reinforcement in the injection mold. Such an arrangement makes it possible to facilitate the manufacturing process while ensuring perfect positioning of the stiffening reinforcement in the midsole, so as to perfectly control the distribution of the mechanical properties, in particular stiffness, of the sole.

[0025] In some embodiments comprising a stiffening reinforcement, the injection mold delimits an injection volume of the second midsole portion, and the stiffening reinforcement comprises a segment which, upon placement of the insert and the stiffening reinforcement in the injection mold, extends outside the injection volume of the second midsole portion.

[0026] According to another aspect, the invention also relates to a shoe sole, in particular for a sports shoe, comprising an intermediate sole comprising a first portion made of a first cellular polymer material and having a first density, and comprising a second portion made of cellular polymer material and having a second density greater than the first density, characterized in that the second portion is overmolded around the first portion so as to ensure the assembly of the intermediate sole by at least partial coating of the first portion in the second portion.It is thus possible to have a first portion of the midsole that is extremely light, but with good elasticity properties and therefore energy restitution, and a second portion that is capable of absorbing the stresses undergone by the midsole, guaranteeing sufficient longevity of the sole, while ensuring reliable assembly of the two portions of the midsole, this assembly being obtained with a reduced number of operations.

[0027] Other features of such a sole may include at least one of the following optional features, taken individually or in combination.

[0028] In some embodiments, the second portion covers a lower face and lateral faces of the first portion, but leaves an upper face of the first portion visible. This arrangement makes it possible to have the upper face of the first portion of the midsole as close as possible to the plantar support face of the user's foot, thus optimizing the feeling of comfort by ensuring good transmission of forces between the user's foot and the first portion.

[0029] In some embodiments, the second portion comprises at least one window which reveals a portion of the lower face and / or the side faces of the first portion.

[0030] In some embodiments, the sole comprises a stiffening reinforcement, the second portion is overmolded around the first portion and the stiffening reinforcement so as to ensure assembly of the midsole by at least partially embedding the first portion and the stiffening reinforcement in the second portion, and the stiffening reinforcement comprises an elongated profile, the profile having a curved guideline that is curved to follow a stiffening reinforcement geometry.In certain variants of such embodiments comprising such a stiffening reinforcement, the sole extends between a front end and a rear end in a sole longitudinal direction, it extends transversely between an internal lateral side and an external lateral side in an internal-external transverse direction perpendicular to the longitudinal direction, it extends in a height direction perpendicular to the longitudinal and transverse directions, and the curved guideline of the profile comprises longitudinal sections which extend from front to rear, which are offset from each other in the transverse direction, and which are connected by turning sections, the profile of the reinforcement comprising at least one front loop formed of a. front turn-over section connecting the front ends of two successive longitudinal sections along the guideline of the profile, and at least one rear loop formed by a rear turn-over section connecting the rear ends of two successive longitudinal sections along the guideline of the profile. Such a geometry of the stiffening reinforcement makes it possible to create stiffness zones, corresponding to each loop, which are at least partly decoupled from each other. In certain examples of such variants, the profile of the stiffening reinforcement comprises: - an external rear loop formed by an external lateral longitudinal section and an external central longitudinal section, connected by an external rear turnaround section; - an internal rear loop formed by an internal lateral longitudinal section (52i) and an internal central longitudinal section (54i), connected by an internal rear turnaround section (56i); - a central front loop (58) which connects the external rear loop (50e) to the internal rear loop (50i) by being formed by the external central longitudinal section (54e) and the internal central longitudinal section (54i), connected by a central front turnaround section (59).

[0031] Such reinforcement geometry allows in particular to have good stiffness in bending around transverse axes, over the length of the sole, while retaining sufficient flexibility in torsion around a longitudinal axis, in particular in a rear part of the sole, to accompany the pronation / supination movements of the foot.

[0032] In some embodiments comprising a stiffening reinforcement, the stiffening reinforcement profile comprises a peripheral front loop which is formed by the external lateral longitudinal section and the internal lateral longitudinal section, connected by a peripheral front turn-over section. Such a peripheral loop makes it possible to maintain a link between the lateral and medial stiffening reinforcement portions, in the manner of an anti-roll bar in motor vehicle suspensions, to better control the pronation / supination movements of the foot.

[0033] In some embodiments comprising a stiffening reinforcement, the stiffening reinforcement profile comprises: - an external front loop formed by an external lateral longitudinal section and an external central longitudinal section, connected by an external front turnaround section; - an internal front loop formed by an internal lateral longitudinal section and an internal central longitudinal section, connected by an internal front turnaround section; - a central rear loop which connects the external front loop to the internal front loop, being formed by the external central longitudinal section and the internal central longitudinal section, connected by a central rear turnaround section.

[0034] Such reinforcement geometry allows in particular to have good stiffness in bending around transverse axes, over the length of the sole, while retaining sufficient flexibility in torsion around a longitudinal axis, in particular in a front part of the sole, to accompany the pronation / supination movements of the foot.

[0035] In some embodiments comprising a stiffening reinforcement, the stiffening reinforcement profile comprises a peripheral rear loop which is formed by the external lateral longitudinal section and the internal lateral longitudinal section, connected by a peripheral rear turn-up section. Such a peripheral loop makes it possible to maintain a link between the lateral and medial stiffening reinforcement portions, to better control the pronation / supination movements of the foot.

[0036] In some embodiments comprising a stiffening reinforcement, the curved guideline of the stiffening reinforcement profile is a line closed on itself. This is advantageous for limiting a concentration of forces applied by the elongated profile on the cellular material(s) of the midsole which could occur at a free termination and this makes it possible to obtain an increased torsional stiffness of the stiffening reinforcement around a longitudinal axis.

[0037] In some embodiments comprising a stiffening reinforcement, in a front longitudinal half of the sole, the stiffening reinforcement is arranged between a lower face of the first midsole portion and an upper face of the second midsole portion. The stiffening reinforcement is thus protected from the risk of breakage and the risk of discomfort for the user is avoided.

[0038] In some embodiments including a stiffening reinforcement, the stiffening reinforcement includes an exposed segment outside the midsole. Brief description of the drawings

[0039] [Fig. 1]: Figure 1 is a schematic perspective view of a first embodiment of a sole, a corresponding upper also being illustrated, corresponding to a left shoe.

[0040] [Fig. 2]: Figure 2 is an exploded perspective view of the midsole of the first embodiment of a sole, seen from above.

[0041] [Fig. 3]: Figure 3 is an exploded perspective view of the midsole of the first embodiment of a sole, seen from below.

[0042] [Fig. 4]: Figure 4 is a perspective view of the first embodiment of a sole, seen from below.

[0043] [Fig. 5]: Figure 5 is a perspective view of the first embodiment of a sole, seen from above.

[0044] [Fig. 6]: Figure 6 is a partial view, in perspective from above, of the rear part of the first embodiment of a sole.

[0045] [Fig. 7A]: Figure 7A is a longitudinal sectional view, through a median longitudinal and vertical plane, of the sole according to the first embodiment.

[0046] [Fig. 7B]: Figure 7B is a cross-sectional view, through a transverse and vertical plane along line BB of Figure 8, of the first embodiment of a sole.

[0047] [Fig. 70]: Figure 70 is a cross-sectional view, through a transverse and vertical plane along line CC of Figure 8, of the first embodiment of a sole.

[0048] [Fig. 7D]: Figure 7D is a cross-sectional view, through a transverse and vertical plane along line DD of Figure 8, of the first embodiment of a sole.

[0049] [Fig. 7E]: Figure 7E is a cross-sectional view, through a transverse and vertical plane along line EE of Figure 8, of the first embodiment of a sole.

[0050] [Fig. 7F]: Figure 7F is a cross-sectional view, through a transverse and vertical plane along line FF of Figure 8, of the first embodiment of a sole.

[0051] [Fig. 8]: Figure 8 is a bottom view of the first embodiment of a sole.

[0052] [Fig. 9]: Figure 9 is a view of the external lateral side of the first embodiment of a sole.

[0053] [Fig. 10]: Figure 10 is a view of the internal lateral side of the first embodiment of a sole.

[0054] [Fig. 11]: Figure 11 is a bottom view of a first embodiment of a stiffening reinforcement, also illustrated in Figures 2, 3, 5, 7A to 7F, 9 and 17, for a left shoe.

[0055] [Fig. 12]: Figure 12 is a side view, seen from the internal lateral side, of the first embodiment of a stiffening reinforcement.

[0056] [Fig. 13]: Figure 13 is a perspective view of a second embodiment of a stiffening reinforcement, also for a left shoe.

[0057] [Fig. 14]: Figure 14 is a perspective view of a third embodiment of a stiffening reinforcement.

[0058] [Fig. 15]: Figure 15 is a schematic perspective view of a manufacturing step of an intermediate sole comprising a stiffening reinforcement according to the second embodiment.

[0059] [Fig. 16]: Figure 16 is a schematic perspective view of a manufacturing step of an intermediate sole comprising a stiffening reinforcement according to the third embodiment.

[0060] [Fig. 17]: Figure 17 is a schematic cross-sectional view of a manufacturing step of an intermediate sole comprising a stiffening reinforcement according to the first embodiment.

[0061] [Fig. 18]: Figure 18 illustrates a method of manufacturing a shoe sole including a stiffening reinforcement. Detailed description

[0062] 1 illustrates a shoe 10, in particular a sports shoe, for example a running shoe, which essentially comprises an upper 12 and a sole 14. For the shoe 10 and for each of its components, it is therefore possible to define a longitudinal direction X, which corresponds to the direction of elongation of the foot of the user of the shoe, a transverse direction Y perpendicular to the longitudinal direction X, which corresponds to the width direction of the foot of the user of the shoe, and a height direction Z which is perpendicular to both the longitudinal direction X and the transverse direction Y, and which, when the shoe is flat on a horizontal surface, is vertical. Longitudinally, the sole 14 and each of its components have a front end and a rear end which correspond respectively to the toes and the heel of the user's foot.Transversely, the sole 14 and each of its components have an internal lateral side and an external lateral side, with reference respectively to the corresponding internal lateral side, sometimes called the medial side, and the corresponding external lateral side of the user's foot. According to the height direction, which will subsequently be considered to be vertical, the sole 14 and each of its components have an upper side, facing the upper of the shoe and therefore towards the user's foot, and a lower side facing the ground. The sole 14 comprises on the one hand an intermediate sole 16, which will be detailed later, and an external sole 18, sometimes called the outsole, arranged against a lower face of the intermediate sole 16.

[0063] An example of a midsole 16 is illustrated in Figures 2 and 3. In these figures, an embodiment is illustrated in which the midsole 16 comprises a first portion 20 of midsole, a second portion 22 of midsole. In the remainder of the application, a particular example of such a midsole will be described more particularly which additionally comprises a stiffening reinforcement 24, in particular a stiffening reinforcement made of composite material formed from reinforcing fibers embedded in a polymer resin, integrated into the midsole 16, as will be described in more detail below. However, the invention also relates to shoe soles, in particular sports shoe soles, without stiffening reinforcement, in particular without stiffening reinforcement made of composite material.

[0064] In the example illustrated in Figures 2 and 3, the first portion 20 of midsole 16 is made of a first cellular polymer material, for example a cellular elastomer, in particular a thermoplastic cellular elastomer. The first polymer material is or comprises for example a thermoplastic copolyamide such as a polyether block amide (for example as known under the trade name PEBAX™ or VESTAMID® E-series), and / or thermoplastic polyurethane (TPU), and / or a thermoplastic copolyester (TPE-E, for example as known under the trade name Hytrel™). However, the first cellular polymer material may be at least partly crosslinked, for example by incorporating a crosslinking agent. This first cellular material has a first density.

[0065] The second midsole portion 22 is made of a second cellular polymer material, for example a cellular elastomer, in particular a thermoplastic cellular elastomer. This second cellular polymer material has a second density. The second polymer material is or also comprises, for example, a thermoplastic copolyamide such as a polyether block amide (for example, as known under the trade name PEBAX™ or VESTAMID® E-series), and / or a thermoplastic polyurethane (TPU), and / or a thermoplastic copolyester (TPE-E, for example, as known under the trade name Hytrel™). In some variants, the second density is greater than the first density. In some variants, the first cellular polymer material and the second cellular material are two cellular materials of the same polymer material, differing only in the size and / or the method of forming the cells.In some variants, the first cellular polymer material and the second cellular material are two cellular materials of two polymer materials belonging to the same family of polymers, for example both a polyether block amide, or both a polyurethane (PU), in particular both a thermoplastic polyurethane (TPU), or both a thermoplastic copolyester (TPE-E), but in different grades, possibly also differing in size and / or method of forming the cells. In other variants, the first cellular polymer material and the second cellular material are two cellular materials belonging to two distinct families of polymers for producing these two sole portions, for example a first portion 20 in PEBA and a second portion 22 in TPEE, or vice versa.

[0066] Advantageously, the second portion 22 of the midsole 16 is overmolded around the first portion 20 of the midsole 16, so as to ensure the assembly of the midsole 16 by at least partial coating of the first portion 20 in the second portion 22. In the embodiments in which the midsole comprises a stiffening reinforcement 24, the second portion 22 of the midsole 16 is even more advantageously overmolded around the first portion 20 of the midsole 16 and the stiffening reinforcement 24, so as to ensure the assembly of the midsole 16 by at least partial coating of the first portion 20 and the stiffening reinforcement 24 in the second portion 22.

[0067] In certain embodiments, the second portion 22 of the midsole 16 covers a lower face 26 and lateral faces 28 of the first portion 20 of the midsole 16, but leaves an upper face 30 of the first portion 20 visible. In this example, as can be seen more particularly in FIG. 1, the upper face 30 of the first portion 20 of the midsole 16 is therefore intended to accommodate the lower face 32 of the upper 12, possibly with the interposition of a mounting insole (not illustrated).

[0068] In certain embodiments, including the embodiment illustrated in Figures 1 and 2, the second portion 22 of the midsole 16 comprises at least one window 34, 36 which reveals a part of the lower face 26 and / or the lateral faces 28 of the first portion 20 of the midsole 16. In the illustrated example, the second portion 22 thus comprises a lower window 34 which passes through the thickness of the second portion 22 in the height direction so as to open, on a lower side, into a lower face 38 of the second portion 22, and on an upper side into an upper face 40 of the second portion 22. It will be noted that the lower window 34 of the second portion 22 of the midsole 16 is not covered by the outer sole 18.In this way, in the sole 14, the lower window 34 reveals, from the outside of the sole 14, seen from below, the lower face 26 of the first portion 20 of the intermediate sole 16. In the example illustrated, the second portion 22 of the intermediate sole 16 also comprises at least one lateral window 36, which opens into an external lateral face 42 of the second portion 22, and which reveals a lateral face 28 of the first portion 20 of the intermediate sole 16. In the example, the lateral window 36 is arranged in the external lateral side of the second portion 22 of the intermediate sole 16.

[0069] In the illustrated example, the first portion 20 of the midsole extends over the entire length of the upper 12 of the shoe 10 in the longitudinal direction.

[0070] Preferably, the first portion 20 of the midsole extends in a single piece longitudinally between a heel area of the foot of a user of the shoe, including the support area at the calcaneus, to at least the phalanges of the foot of a user of the shoe. In the metatarsal area, the first portion 20 of the midsole preferably extends in a single piece transversely across the entire width of the metatarsal bones of the user's foot. In other words, the first portion 20 of the midsole preferably extends such that the main support surfaces of the user's foot are arranged opposite the upper face 30 of the first portion 20 of the midsole.

[0071] In the illustrated example, the second portion 22 of the intermediate sole 16 has a base which covers, from below, the entire lower face 26 of the first portion 20, and has a peripheral rim 44 which rises vertically along the lateral faces 28 of the first portion 22. In the example, the peripheral rim 44 extends over the entire periphery of the sole 14. In the example, the peripheral rim 44 rises vertically above the level of the upper face 40 of the second portion 22, said upper face 40 therefore being the upper face of the base of the second portion 22. In the example, the peripheral rim 44 rises vertically above the level of the upper face 30 of the first portion 20 of the intermediate sole 16, in the example over the entire periphery of the sole 14. Thus, the second portion 22 of the intermediate sole 16 has a shell shape, the peripheral rim 44 delimiting, above the base of the second portion 22, an internal volume which accommodates the entirety of the first portion 20 of the intermediate sole.

[0072] In total, it is advantageous to form a first portion 20 which occupies the maximum possible volume in the midsole 16, this in order to maximize, in the total volume of the midsole 16, the proportion occupied by the first portion 20 of the midsole 16 which has the lowest density, thus with the possibility of reducing the total weight of the midsole 16. The volume of the first portion 20 of the midsole 16 corresponds to the volume of a theoretical envelope corresponding to the external geometry of said first intermediate portion, therefore comprising the lower face 26, the lateral faces 28, and the upper face 30 of the first portion 20 of the midsole 16. The volume of the cells of the cellular material of the first intermediate portion 20 is of course included in the volume of the first portion 20 of the midsole 16.The total volume of the midsole 16 comprises the volume of the first portion 20 of the midsole 16, the volume of the second portion 22 of the midsole 16, and, for the embodiments in which the midsole 16 comprises a stiffening reinforcement 24, the volume of this stiffening reinforcement 24. The volume of the second portion 22 of the midsole 16 corresponds to the volume of a theoretical envelope corresponding to the external geometry of said second intermediate portion. The volume of the cells of the cellular material of the second intermediate portion is of course included in the volume of the second portion 20 of the midsole 16. Of course, the volumes are considered here, empty, without force applied to the midsole, therefore in the uncompressed state of the cellular materials.

[0073] Preferably, the first portion 20 of the midsole occupies at least one-third of the total volume of the midsole 16, preferably at least 40 percent of the total volume of the midsole 16. Typically, the first portion 20 of the midsole occupies between 40 percent and 60 percent of the total volume of the midsole 16, preferably between 50 percent and 60 percent of the total volume of the midsole 16. It is noted that, in the embodiments in which the midsole comprises a stiffening reinforcement 24, the latter preferably occupies a volume which is preferably less than 10 percent of the total volume of the midsole 16, preferably less than 5 percent of the total volume of the midsole 16. Typically, the stiffening reinforcement 24 occupies between 1 percent and 5 percent of the total volume of the midsole 16.

[0074] In the embodiments in which the midsole comprises a stiffening reinforcement 24, the stiffening reinforcement 24 extends between a front end 46 of the stiffening reinforcement 24 and a rear end 48 of the stiffening reinforcement 24, in the longitudinal direction X of the sole. It extends transversely between an internal lateral side and an external lateral side in the internal-external transverse direction Y perpen- dicular to the longitudinal direction X, and it extends along the height direction Z perpendicular to the longitudinal X and transverse Y directions. In such a case, the sole 14 of the shoe 10 comprises an intermediate sole 16 comprising a first portion 20 made of a first cellular polymer material and having a first density, comprising a stiffening reinforcement 24, and comprising a second portion 22 made of cellular polymer material and having a second density greater than the first density. Advantageously, provision is made for the second portion 22 to be overmolded around the first portion 20 and the stiffening reinforcement 24 so as to ensure the assembly of the intermediate sole 16 by at least partial coating of the first portion 20 and the stiffening reinforcement 24 in the second portion (22).In the illustrated example, it can be seen that, at least in a front longitudinal half of the sole 14, the reinforcement 24 is arranged between the lower face 26 of the first portion 20 of the intermediate sole and the upper face 40 of the second portion 22 of the intermediate sole.

[0075] In the illustrated embodiments, the stiffening reinforcement 24 comprises at least one profile 25 elongated along a guideline. The guideline is for example a center line of the profile 25 which passes through a center point of each section of the profile 25. A profile is continuous along its guideline. In the illustrated examples, the profile 25 has a curved guideline which is curved to follow a stiffening reinforcement geometry. The profile 25 of the stiffening reinforcement therefore has a non-rectilinear geometry.

[0076] In the example, the stiffening reinforcement comprises a single profile 25 elongated along a guideline.

[0077] In the example, the stiffening reinforcement 24 consists of a single profile 25 elongated along a guideline, without any other component. However, in variants, it may be provided that the stiffening reinforcement 24 comprises several profiles each elongated along its own guideline, linked together directly or indirectly by means of one or more other components, or not linked together other than by their integration into the sole 14, for example by their integration into the intermediate sole 16.

[0078] Alternatively, it may be provided that the stiffening reinforcement 24 comprises a single profile 25 elongated along a guideline or several profiles each elongated along its own guideline, and at least one reinforcing element in the form of a stiffening plate. The stiffening plate and the elongated profile or elongated profiles may be arranged in at least one and the same part of the sole, for example a front part of the sole in front of a plantar arch zone, and / or a central part of the sole corresponding to a plantar arch zone, and / or a rear part of the sole behind a plantar arch zone. In such a case, the stiffening plate and the elongated profile 25 or elongated profiles may be arranged at least partly or completely in a superposed relationship along the height direction, or the elongated profile may for example be arranged partly or entirely around the stiffening plate.In other variants, the stiffening plate and the elongated profile or profiles may be arranged in different parts of the sole. In other variants, the stiffening reinforcement 24 comprises a single elongated profile 25. For example, the stiffening reinforcement 24 comprises one or more stiffening plates.

[0079] In the illustrated example, the curved guideline of the profile 25 of the stiffening reinforcement comprises longitudinal sections which extend from front to back, which are offset from each other in the transverse direction Y, and which are connected by turn-over sections. A turn-over section is therefore a section of the profile along which the curved guideline makes a half-turn around the height direction Z, thus having a substantially U- or V-shape.

[0080] In the illustrated examples, the curved guideline of the profile 25 of the stiffening reinforcement 24 is a line closed on itself, which means that the profile 25 of the stiffening reinforcement does not have a free end. This is advantageous for limiting a concentration of the forces applied by the elongated profile 25 on the cellular material(s) of the midsole which could occur at such a free end.

[0081] Preferably, the profile 25 of the stiffening reinforcement 24 comprises several longitudinal sections which extend in the longitudinal direction X of the sole 14. Certain longitudinal sections may have rectilinear parts, but they may, as illustrated in the figures, have curved parts while having a general longitudinal orientation in the longitudinal direction X. Generally, two longitudinal sections may be connected by a turning section to form a loop having a substantially U-shaped geometry.

[0082] In a first example of embodiment of the stiffening reinforcement 24, illustrated for example in figures 2, 3, 7B to 7F, 11 and 12, and 16, and in a second example illustrated in figures 13 and 15, the profile 25 of the stiffening reinforcement 24 comprises: ♦ an external rear loop 50e, formed by an external lateral longitudinal section 52e and an external central longitudinal section 54e, connected by an external rear turnaround section 56e; ♦ an internal rear loop 50i, formed by an internal lateral longitudinal section 52i and an internal central longitudinal section 54i, connected by an internal rear turnaround section 56i; ♦ a central front loop 58 which connects the external rear loop 50e to the internal rear loop 50i by being formed by the external central longitudinal section 54e and the internal central longitudinal section 50i, connected by a central front turnaround section 59.

[0083] At a forward loop, the longitudinal sections of the loop under consideration extend longitudinally backward relative to the forward turnaround section of the loop under consideration. At a backward loop, the longitudinal sections of the loop under consideration extend longitudinally forward relative to the backward turnaround section of the loop under consideration.

[0084] In this first and second embodiment, the guideline of the profile 25 of the stiffening reinforcement is a line closed on itself, so that the stiffening reinforcement comprises a peripheral front loop 70 which is formed by the external lateral longitudinal section 52e and the internal lateral longitudinal section 52I, connected by a peripheral front turn-over section 72. Preferably, the peripheral front turn-over section 72 is arranged longitudinally in front of the central front turn-over section 59.

[0085] In this first embodiment and this second embodiment, in which the curved guideline of the profile 25 of the stiffening reinforcement 24 is a line closed on itself, the curved guideline closed on itself comprises as only turning sections the external rear turning section 56e, the internal rear turning section 56i, the central front turning section 59 and the peripheral front turning section 72.

[0086] In this embodiment, it is understood that the internal 50i and external 50e rear loops of the stiffening reinforcement 24 are free relative to each other in a rear portion of the sole, in the transverse direction Y and in the height direction Z. Indeed, the internal 50i and external 50e rear loops are connected to each other only by the front central loop 58 and by the front peripheral loop 70, more specifically connected only by the central front turn-up section 59 and by the peripheral front turn-up section 72, which are located in a front portion of the sole, in front of a plantar arch zone of the sole. They can therefore move substantially independently of each other in the transverse direction Y and in the height direction Z. By the independence in the vertical direction, a decoupling between the internal lateral side and the external lateral side of the sole is allowed.By the independence in the transverse direction, the inner 50i and outer 50e rear loops of the stiffening reinforcement 24 are allowed to move apart transversely from each other, however with a spring effect, in the event of significant deformation of the heel area of the midsole in the height direction under a significant vertical impact. This spacing with spring effect of the inner 50i and outer 50e rear loops of the stiffening reinforcement 24 allows the cellular polymer material of the midsole 16 to deform more freely to absorb and cushion such a significant vertical impact.

[0087] In a third example of embodiment of the stiffening reinforcement 24, illustrated for example in figures 14 and 16, the profile 25 of the stiffening reinforcement 24 comprises: ♦ an external front loop 60e formed by an external lateral longitudinal section 52e and an external central longitudinal section 54e, connected by an external front turnaround section 66e; ♦ an internal front loop 60I formed by an internal lateral longitudinal section 52i and an internal central longitudinal section 54i, connected by an internal front turning section 66i; ♦ a central rear loop 68 which connects the external front loop 60e to the internal front loop 60i by being formed by the external central longitudinal section 54e and the internal central longitudinal section 54I, connected by a central rear turnaround section 69.

[0088] In this third embodiment, the guideline of the profile 25 of the stiffening reinforcement 24 is a line closed on itself, so that the stiffening reinforcement 24 comprises a peripheral rear loop 74 which is formed by the external lateral longitudinal section 52e and the internal lateral longitudinal section 52i, connected by a peripheral rear turn-over section 76. In this third embodiment, in which the curved guideline of the profile 25 of the stiffening reinforcement 24 is a line closed on itself, the curved guideline closed on itself comprises as only turn-over sections the external front turn-over section 66e, the internal front turn-over section 66i, the central rear turn-over section 69 and the peripheral rear turn-over section 76.

[0089] In this embodiment, it is understood that the internal 60i and external 60e front loops of the stiffening reinforcement 24 are free relative to each other in a front portion of the sole 14, in the transverse direction Y and in the height direction Z. Indeed, the internal 60i and external 60e front loops are connected to each other only by the rear central loop 68 and by the peripheral rear loop 74, more specifically connected only by the central rear turning-over section 69 and by the peripheral rear turning-over section 76, which are located in a portion of the sole behind a metatarsal flexion zone of the sole 14. They can therefore move substantially independently of each other in the height direction Z. By the independence in the vertical direction, a decoupling between the internal lateral side and the external lateral side of the sole is allowed.

[0090] Each of the loops, in particular, in the first embodiment and the second embodiment, the external rear loops 50e, internal rear loops 50i, and central front loops 58, and, in the third embodiment, the external front loops 60e, internal front loops 60i, and central rear loops 68, is therefore formed of two longitudinal sections 52e, 52i, 54e, 54i, connected by a turning section 56e, 56i, 59, 66e, 66i, 69, so as to form a substantially U-shaped geometry for the loop in question, the U being open opposite the turning section for the loop in question. Preferably, the longitudinal sections belonging to the same loop, therefore connected by the same turning section, are offset relative to each other in the transverse direction Y.Thus, the two central longitudinal sections are arranged transversely between the two lateral longitudinal sections, which are each offset outwards relative to a median vertical longitudinal plane of the stiffening reinforcement 24.

[0091] As can be seen more particularly in Figures 11 and 12, the internal lateral longitudinal section 52i preferably has a geometry which generally follows the profile of the internal lateral side of the lower face of a user's foot. Thus, the internal lateral longitudinal section 52i may advantageously have, in a view from below, in a central portion in the longitudinal direction, an inwardly recess corresponding to the arch of the foot. The external lateral longitudinal section 52e may advantageously have, in a view from below, in a central portion in the longitudinal direction, an inwardly reinforcement, which may be of lesser amplitude than that of the internal lateral longitudinal section 52i. In a lateral view, this central portion may be raised upwards in the height direction, again to correspond to the arch of the foot.In the illustrated example, the two central longitudinal sections 54e, 54i are substantially rectilinear between their front and rear ends. Similar geometries are found in the second embodiment illustrated in Figure 13 and Figure 15.

[0092] In the various examples illustrated, the stiffening reinforcement 24 has a line of minimum transverse width of the stiffening reinforcement, called the arch line LA, illustrated in FIG. 11 in particular, which represents the line joining the two points, belonging respectively to the internal lateral longitudinal section 52i and to the external lateral longitudinal section 52e, which are, in a view along the height direction, transversely closest along the transverse direction Y. The arch line LA is intended to be arranged substantially below the arch of a user's foot.

[0093] In the various examples illustrated, the stiffening reinforcement 24 has, in front of the arch line LA, a line of maximum transverse width of the stiffening reinforcement in front of the arch line LA, called the metatarsal line LM. The metatarsal line LM represents the line joining the two points, belonging respectively to the internal lateral longitudinal section 52i and to the external lateral longitudinal section 52e, which are, in a view along the height direction, in front of the arch line LA and transversely the furthest from each other. The metatarsal line LM is intended to be arranged substantially below the metatarsal articulation zone of the user's foot.

[0094] In the first and second embodiments, the central front turn-up section 59 extends forward of the arch line such that the central longitudinal sections 541, 54e extend from the rear end of the reinforcement into a front area of the reinforcement in front of the arch of a user's foot.

[0095] In the first and second embodiments, the central front turning section 59 extends in front of the metatarsal line LM, therefore in front of the metatarsal articulation zone of the user's foot, such that the central longitudinal sections 54i, 54e extend, from the rear end of the reinforcement, into a front zone of the reinforcement in front of the metatarsal articulation zone of a user's foot.

[0096] In the first and second embodiments, the external rear turn-up section 56e and the internal rear turn-up section 561 extend behind the arch line, such that the four longitudinal sections of the profile 25 of the stiffening reinforcement 24 extend in a rear portion of the reinforcement, behind the arch zone of a user's foot, in this case behind a heel zone of the user's foot.

[0097] Between the first embodiment and the second embodiment of a stiffening reinforcement 24, it is noted that the longitudinal position of the central front turning section 59 is not exactly the same. However, in both embodiments, the central front turning section 59 extends in front of the metatarsal line LM, therefore in front of the metatarsal articulation zone of the user's foot.

[0098] In the third embodiment, the central rear turn-around section 69 extends behind the arch line LA.

[0099] In the various embodiments illustrated, which have the particularity of having a stiffening reinforcement 24, the zone of the stiffening reinforcement 24 which is comprised between the arch line LA and the metatarsal line LM is a flexion zone ZF of the reinforcement which follows the flexion of the foot of a user wearing the shoe provided with this stiffening reinforcement 24.

[0100] As can be seen more particularly by comparing Figures 11 and 12, the stiffening reinforcement 24 can advantageously comprise a transverse tilting zone ZB arranged in front of the arch line LA, in which each longitudinal section 52e, 52i, 54e, 54i comprises an upwardly curved inflection point at a low point in the height direction. In the examples, the tilting zone ZB is arranged behind the metatarsal line LM. This tilting zone ZB, arranged near the metatarsal flexion zone of the user's foot, will promote a forward tilting movement of the user's foot during the rolling of the foot, a movement which promotes a general tilting of the user's body, to the benefit of the dynamism of the user's running. In the embodiments, the tilting zone ZB stiffening reinforcement 24 is therefore arranged in the bending zone ZF of the stiffening reinforcement stiffening 24, between the arch line LA and the metatarsal line LM of the stiffening reinforcement 24. However, one can for example have a more advanced tilt zone ZB, for example at the level of the metatarsal line LM with the low point of each section on the metatarsal line LM.

[0101] As can be seen more particularly in Figure 12, the front part of the stiffening reinforcement 24, located forward from the tilting zone ZB, is configured in such a way that in each transverse and vertical plane, the sections of the different sections in this plane are arranged at the same height according to the height direction.

[0102] In the first and second embodiments of a stiffening reinforcement, the stiffening reinforcement 24 has a heel area in which a rear portion of the external lateral longitudinal section 52e can be raised upwards in the height direction Z and be curved transversely in top view with a concavity facing a median longitudinal axis of the reinforcement 24, to encircle and reinforce the outside of a heel area of the midsole 16. Similarly, in the heel area of the stiffening reinforcement 24, the rear portion of the internal lateral longitudinal section 52i can be raised upwards in the height direction Z and be curved transversely in top view, with a concavity facing a median longitudinal axis of the reinforcement 24, to encircle and reinforce the inside of a heel area of the midsole 16.On the other hand, the central longitudinal sections, internal 54i and external 54e, substantially rectilinear, are parallel to each other and have a geometry which follows a direction parallel to the longitudinal direction, so that these central longitudinal sections, internal 54i and external 54e, remain essentially in a lower part of the heel zone of the midsole, with however a rear end portion curved upwards in the height direction to connect, at the level of the internal 56i and external 56e rear turn-up sections, with the rear end of the lateral longitudinal sections, internal 52i and external 52e.

[0103] The stiffening reinforcement 24 according to the first embodiment, as well as that according to the second embodiment, thus comprises a heel zone, behind the arch line LA, in which the external lateral longitudinal section 52e is arranged at a higher level than the external central longitudinal section 54e in the height direction. In this zone, the external lateral longitudinal section 52e can thus form a cradle transversely towards the outside for the corresponding heel zone of the sole. Advantageously, it can also be seen that, for these two embodiments, in the heel zone, behind the arch line LA, the internal lateral longitudinal section 52i is arranged at a higher level than the internal central longitudinal section 54i in the height direction. In this zone, the internal lateral longitudinal section 52i can thus form a cradle transversely towards the inside for the corresponding heel zone of the sole.By combining these two characteristics, the heel zone of the stiffening reinforcement forms a cradle for the heel zone of the midsole 16, reinforcing the latter in the transverse direction, thus reinforcing the stability of the sole 14 during transverse supports at the level of the heel zone.

[0104] In Figure 12 it can be seen that, in the heel area, the external lateral longitudinal section 52e is arranged at a higher level than the internal lateral longitudinal section 52i, according to the height direction Z, thus accentuating the transverse stabilization effect on the external lateral side of the sole compared to the internal lateral side.

[0105] In the third embodiment, the longitudinal lateral sections 52e, 52i are, in their rear part, substantially in the same horizontal plane, only the peripheral rear turning-up section 76 being raised upwards in the height direction Z, to encircle and reinforce the rear face of the heel zone of the intermediate sole 16.

[0106] Generally, the stiffening reinforcement 24 is a more rigid part than the first portion 20 and the second portion 22 of the midsole 16, which are made of elastomeric cellular polymer material. The stiffening reinforcement 24 is for example made of a composite material comprising reinforcing particles or fibers embedded in a polymer resin matrix. In the examples illustrated in which the stiffening reinforcement 24 comprises an elongated profile 25, the elongated profile 25 of the stiffening reinforcement preferably comprises reinforcing fibers embedded in a polymer resin matrix. The profile 25 is therefore formed of a composite material, which has a good ratio between its rigidity and its weight.The reinforcing fibers of the stiffening reinforcement 24 preferably comprise carbon, glass, and / or aramid fibers, the tensile stiffness of which is favorable for obtaining a stiffening reinforcement 24, in particular an elongated profile 25, having high rigidity for low weight and size. In particular when the stiffening reinforcement 24 comprises an elongated profile 25, the polymer resin forming the matrix of the composite material of the stiffening reinforcement is preferably a thermoplastic polymer resin, for example a resin of, or based on, polycarbonate (PC), thermoplastic polyurethane (TPU), polypropylene (PP) or polyamide.The thermoplastic nature of the resin is an advantage for producing a profile 25 elongated along a direction of the curved guideline, since the final geometry of the profile 25, and therefore of the stiffening reinforcement 24, can be obtained in a manufacturing step independent of the manufacturing of the profile 25 itself. In other words, the profile itself can first be manufactured independently of its final geometry in the stiffening reinforcement 24. The use of a thermoplastic polymer resin can also be advantageous for other forms of stiffening reinforcement 24, including plate-shaped.

[0107] Advantageously, the reinforcing fibers of the stiffening reinforcement 24 comprise fibers oriented in a preferred direction. In the context of a stiffening reinforcement 24 comprising an elongated profile 25, the reinforcing fibers in the profile 25 of the stiffening reinforcement comprise reinforcing fibers oriented in the direction of the curved guideline within the resin matrix. Thus, preferably at any point of the profile 25 along the curved guideline, the reinforcing fibers oriented in the direction of the curved guideline are parallel, at this point, to the direction of the curved guideline at this point of the profile 25, or form an angle less than or equal to 25 degrees relative to the direction of the curved guideline at this point.With such an arrangement of the reinforcing fibers, maximum rigidity of the profile 25 of the stiffening reinforcement 24 is obtained in bending around an axis perpendicular to the curved guideline.

[0108] Advantageously, in certain embodiments, the reinforcing fibers of the stiffening reinforcement 24 comprise long fibers, the length of which is greater than 1 millimeter, preferably greater than 10 millimeters. In the context of a stiffening reinforcement 24 comprising an elongated profile 25, the reinforcing fibers, which are oriented in the direction of the curved guideline within the resin matrix, are, in certain embodiments, continuous fibers along the length of the curved guideline. The use of continuous fibers, oriented in the direction of the curved guideline in the context of a stiffening reinforcement 24 comprising an elongated profile 25, makes it possible to increase the ratio between the rigidity of the profile 25 and its weight and size. The reinforcing fibers of the profile 25 can thus comprise continuous fibers parallel to each other along the length of the curved guideline.The reinforcing fibers of the profile 25 may thus comprise continuous fibers along the length of the curved guideline and parallel to the curved guideline along the length thereof. It will be noted that the continuous fibers may be strictly parallel to the curved guideline, or have a certain angle with this curved guideline, an angle which is preferably less than or equal to 25 degrees of angle. The continuous fibers oriented along the curved guideline may thus be wound in a helix or braided around the curved guideline, while forming an angle less than or equal to 25° of angle.

[0109] It is noted that the stiffening reinforcement 24, in particular in the case where it has a shape other than that of an elongated profile, for example a plate or the like, can be made of polymer material without reinforcing fibers. Such stiffening reinforcement can then be made, for example, in whole or in part by injection molding in polymer material, for example PEBA.

[0110] To obtain a profile 25 having continuous reinforcing fibers along the length of the curved guideline, the reinforcing fibers being embedded in a resin matrix, a pultrusion process will be used, for example. Such a pultrusion process makes it possible to obtain a profile 25 of constant section. Insofar as this profile 25 is manufactured from a composite material based on thermoplastic polymer resin, it is possible, after the pultrusion step, to shape the profile. This shaping may firstly comprise curving the profile by curving the guideline in order to obtain a curved guideline of the profile, thus forming in particular the turning sections, but also possibly by configuring the longitudinal sections to the shape described above. [YES] Furthermore, if the pultrusion process itself generally generates a profile of constant section, different section geometries can be provided. The section of the profile 25 as obtained for example by a pultrusion process, seen in a plane perpendicular to the guideline of the profile 25, can for example be a section whose periphery is a closed line convex on itself, such as a circular section, an ovoid section or a convex polygonal section. It can be a section whose periphery is a line closed on itself but having concavities, such as an “I”, “H”, “8”, “M” section, etc. However, to the extent that the profile 25 is manufactured from a composite material based on thermoplastic polymer resin, it is possible, after the pultrusion step, to shape, at least locally, the section of the profile 25.

[0112] Thus, as can be seen by comparing Figures 7B to 7F, the first embodiment of a stiffening reinforcement 24 comprises an elongated profile 25 which has a section which evolves along the curved guideline, depending on the position of the point considered profile in relation to the sole, therefore depending on the position of the considered point of the profile in relation to the user's foot.

[0113] Thus, in the first embodiment of a stiffening reinforcement 24, in front of the arch line LA, or at least in the entire flexion zone ZF, the elongated profile 25 of the stiffening reinforcement 24 has, in section through any plane containing the transverse and height directions, a section having a transverse width, in the transverse direction Y, which is greater than its height in the height direction Z. Thus, at least in the flexion zone ZF, and preferably in the entire front zone in front of the arch line LA, the elongated profile 25 of the stiffening reinforcement 24 has a flattened section in the height direction, this in order to locally reduce the flexion stiffness of the stiffening reinforcement, around a transverse axis, in the metatarsal flexion zone of the sole.Thus, at least in the bending zone ZF, the elongated profile 25 of the stiffening reinforcement may have a rectangular, elliptical or oblong section, having a transverse dimension greater than its height dimension. In this case, it can be seen in Figures 7B to 7D that, for the first embodiment of a stiffening reinforcement 24, the elongated profile 25 of the stiffening reinforcement 24 has a flattened section in the height direction throughout the portion of the stiffening reinforcement 24 in front of the arch line LA, up to and including the arch line LA.

[0114] Conversely, in a rear zone of the sole, the elongated profile 25 of the stiffening reinforcement 24 may have, at least locally, in section through a plane containing the transverse directions Y and height Z, a section whose ratio between the transverse width, in the transverse direction Y, and the height in the height direction Z, is greater than the comparable ratio for the profile 25 in front of the arch line LA or in the entire flexion zone ZF, this in order to locally increase the flexion rigidity about a transverse axis. 7F thus illustrates the case of a stiffening reinforcement 24 whose elongated profile 25 has, in the heel zone, behind the arch zone and therefore behind the arch line LA, a non-flattened section in the height direction, in this case for example a circular section.

[0115] Thus, by adapting the sectional shape of the profile 25 along the curved guideline, depending on the position of the section considered relative to the sole 14, it is possible, starting from a profile 25 of constant section, to produce a stiffening reinforcement 24 which has optimal rigidity and flexion characteristics to accompany the rolling movement of the foot.

[0116] In the illustrated examples, the elongated profile 25 has a section, in a plane perpendicular to the curved guideline, the surface area of which is preferably in the range from 5 mm 2 at 20 mm 2 , preferably in the range of 7 mm 2 at 15 mm 2. For example, the elongated profile 25 may have, before local deformation, a circular section whose diameter is for example in the range from 2.5 mm to 4 mm, corresponding, rounded to the nearest unit, to a section in the range of 20 mm. 2 at 50 mm 2 .

[0117] In the example illustrated in Figures 7B to 7B, the elongated profile 25 has a section, in a plane perpendicular to the curved guideline, which is a solid section. In this example, the solid section is therefore entirely filled with the material constituting the profile 25, in this case, for example, a composite material formed from reinforcing fibers embedded in a polymer resin, which may be a thermoplastic polymer resin. tique. It is noted that, in the case of a composite material, the distribution of the reinforcing fibers in the section may be homogeneous in the section, or may on the contrary be heterogeneous, for example with more reinforcing fibers in a peripheral region of the section than in a central region of the section. However, the elongated profile 25 may, in certain embodiments, have a hollow section in a plane perpendicular to the curved guideline, for example with a recess in a central region of the section.

[0118] In some embodiments, the elongated profile 25 may be formed of different materials in different portions of its cross-section, for example, with a first material in a first half of the cross-section and a second material in a second half of the cross-section, or for example, with a first material in a central region of the cross-section and a second material in a peripheral region of the cross-section, around the first material. For example, the first material may be a low-density material, such as a thermoformable rigid foam, and the second material may be a composite material formed of the reinforcing fibers embedded in a polymer resin, which may be a thermoplastic polymer resin.

[0119] In certain embodiments, in particular the first embodiment, the stiffening reinforcement 24 is at least partly embedded in the midsole 16 of the sole, the midsole 16 being made of a cellular polymer material. As can be seen in particular in FIGS. 7B to 7F, the reinforcement 24 is almost entirely arranged between the lower face 26 of the first portion 20 of the midsole and the upper face 40 of the second portion 22 of the midsole, and is therefore thus embedded in the midsole 26 by being interposed between two distinct portions 20, 22 of the midsole, at the interface between the two portions.Advantageously, it can be seen that the elongated profile 25 of the stiffening reinforcement 24 is received, over all or part of its extension along its curved guideline, at the bottom of a groove 21 arranged, in the illustrated example, in the lower face 26 of the first portion 20 of the intermediate sole 16, said groove 21 being able to be, over all or part of the extension of the profile 25, formed in the upper face 40 of the second portion 22 of the intermediate sole 16. However, it can be provided that at least a portion of the stiffening reinforcement 24 is embedded in a portion of the intermediate sole, with continuity of the material of said portion of the intermediate sole around said embedded portion of the stiffening reinforcement 24.In particular, it may be provided that at least a portion of the stiffening reinforcement 24 is embedded in the second portion 22 of the intermediate sole 16, with continuity of the material of said second portion 22 of the intermediate sole around said embedded portion of the stiffening reinforcement 24. In particular, in the termination modes in which the stiffening reinforcement 24 comprises an elongated profile 25, it may be provided that a segment of the elongated profile 25 of the stiffening reinforcement 24 is embedded in the second portion 22 of the intermediate sole 16, with continuity of the material of said second portion 22 of the intermediate sole around said embedded portion of the stiffening reinforcement 24.In the first example of embodiment of a stiffening reinforcement described below, the internal rear turn-up segments 56i and 56e of the elongated profile 25 are thus preferably embedded in the second portion 22 of the intermediate sole 16, with continuity of the material of said second portion 22 of the intermediate sole around these internal rear segments 56i and 56e.

[0120] The stiffening reinforcement 24 may comprise a portion arranged outside the intermediate sole 16, for example between the intermediate sole 16 and the upper 12, or between the intermediate sole 16 and the outer sole 18, or even outside the sole 14. In the first embodiment, the stiffening reinforcement 24 may comprise, over a portion of the extension of the elongated profile 25, a segment arranged outside the intermediate sole 16, for example between the intermediate sole 16 and the upper 12, or between the intermediate sole 16 and the outer sole 18, or even outside the sole 14.For example, as can be seen more particularly in Figure 5, Figure 6 and Figure 7F, in the heel area, behind the arch line LA, the external lateral longitudinal section 52e of the first embodiment of a stiffening reinforcement 24 has an apparent segment 52ea which extends outside the midsole 16 and outside the sole 14, protruding outwards relative to the midsole 16 and relative to the sole 14 taken as a whole. In this case, the apparent segment 52ea extends outwards relative to an external lateral face of the heel area of the midsole 16, which lateral face is an external lateral face of the sole 14 taken as a whole. Thus, in this lateral face of the heel area of the midsole 16, the visible segment 52ea of the stiffening reinforcement 54 is visible from the outside of the shoe.In particular, it can be seen in particular in Figure 7F that an empty space 78 is provided between the visible segment 52ea of the external lateral longitudinal section 52a of the profile 25 of the stiffening reinforcement and said external lateral face of the intermediate sole 16. By thus providing an empty space 78 between the visible segment 52 and the body of the intermediate sole 16, the risks of tearing which could occur at an interface where the visible segment 52ea would be in contact with the body of the intermediate sole 16 without being embedded inside the latter are avoided.

[0121] The stiffening reinforcement 24 makes it possible to increase the rigidity of the sole 14 in flexion, in particular in flexion around a transverse axis, and in particular in flexion around a transverse axis in the metatarsal area. The rigidity in flexion helps to efficiently transfer the propulsive force generated by the athlete. The stiffening reinforcement 24 also acts as a spring blade which restores the energy after being “loaded” in flexion. The stiffening reinforcement 24 can also have the advantage of increasing the stability of the sole 14, in particular in torsion around a longitudinal axis.This makes it possible in particular to compensate for any flexibility of the material or materials of the midsole 16, thus making it possible to produce the midsole 16, or at least a portion thereof, from a very low density cellular material, for example by a supercritical fluid foaming process in an autoclave as will be described below. In addition, the stiffening reinforcement 24 as described below makes it possible to obtain a “rocking effect”, in particular thanks to the curvature of the insert in the rocking zone ZB, as described above, and thanks to its rigidity, when the athlete exerts pressure on the front of the insert, which tends to generate a counterforce which pushes the heel upwards for a faster take-off.

[0122] For the manufacture of a stiffening reinforcement 24 as described above, comprising an elongated profile 25, it will be possible to advantageously implement a manufacturing method 100, as illustrated in Figure 18, such a method comprising: a. manufacturing 110, for example by pultrusion, an elongated profile 25 made of composite material comprising, for example, continuous reinforcing fibers embedded in a polymer resin matrix, which may be a thermoplastic polymer resin; b. heating 120 the elongated profile to bring it into a plastic state, and curving 130 the elongated profile, in the plastic state, to bend the guideline of the profile so that it follows the stiffening reinforcement geometry.

[0123] Such a manufacturing method 100 of a stiffening reinforcement 24 having a profile 25 elongated along a curved guideline in at least two steps makes it possible to implement, in the manufacturing step 110, a manufacturing method making it possible to obtain a rectilinear profile, for example a pultrusion method. The final shape of the stiffening reinforcement 24 is only obtained during a step subsequent to the first step, by taking advantage of the shape-changing capacity of the profile thanks to the use of a thermoplastic polymer resin as a matrix of the composite material forming the elongated profile 25. The curving step 130 makes it possible to obtain the profile 25 having a curved guideline which is curved to follow a stiffening reinforcement geometry. The heating 120 and / or the curvature 130 can each be carried out in one or more steps.

[0124] The manufacturing method 100 may also include a step of local shaping 140 of the section of the elongated profile in its plastic state, also subsequent to the pultrusion manufacturing step 110, to give it, locally, a section having a transverse width greater than its height in the height direction. Preferably, the step of local shaping 140 of the section of the profile 25 is also subsequent to the heating step 120 and the step of curving 130 of the elongated profile 25. Indeed, this makes it very easy to act locally on the portion of the stiffening reinforcement 24 that one wishes to flatten, depending on the final geometry of the reinforcement and therefore the position of the flattening zone relative to the sole 14 and the user's foot.The step of local shaping 140 of the section of the elongated profile in its plastic state can be carried out in several steps, and can in particular comprise one or more steps of heating the profile 25.

[0125] When the curved guideline of the profile 25 of the stiffening reinforcement 24 is a line closed on itself, the manufacturing method 100 may comprise, during or after the curvature step 130, and / or during or after the local shaping step 140, a step of closing the guideline during which two ends of the profile, initially distinct, are connected to each other at a connection point. The connection of the two ends may be carried out by any appropriate chemical or mechanical bonding technique, for example by gluing, by welding, by joining by a sleeve, etc. For example, a connection by welding may be carried out during the local shaping step 140, for example by heating and pressing against each other the 2 ends of a section of profile which will have been curved according to a closed curved guideline.

[0126] However, the stiffening reinforcement 24 may be produced in any manner known to those skilled in the art, depending on its geometry and its material. A stiffening reinforcement 24 in the form of a plate and made of a long-fiber composite material may be implemented using conventional techniques, for example by draping a reinforcing fiber fabric and impregnating it with polymer resin. In other cases, particularly in the case of a stiffening reinforcement composed of a non-reinforced or reinforced polymer resin by short fibers or particles, injection molding or compression molding techniques (for example RTM “Resin Transfer Molding” or SMC “Sheet Molding Compound” for composite materials) can be implemented.

[0127] We will now describe a manufacturing method 300 which can be implemented for the manufacturing of a midsole 16 as described above. We are therefore here in the context of a midsole 16 for a shoe sole 14, the midsole 16 comprising a first portion 20 made of a first cellular polymer material, comprising a stiffening reinforcement 24, and comprising a second portion 22 of midsole 16 made of a second cellular polymer material.

[0128] This manufacturing method 300 may comprise the steps of: a. manufacturing 200 of an insert comprising the first cellular polymer material, the insert being for example formed by the first portion 20; b. placing 310 of the insert 20 in an injection mold 82 having the shape of the intermediate sole 16, as shown more particularly schematically in figures 15, 16 and 17; c. forming 320, around the insert 20, of the second portion 22 of the intermediate sole made of cellular polymer material by a molding method.

[0129] In the embodiments in which the midsole 16 additionally comprises a stiffening reinforcement, the manufacturing method 300 may comprise the steps of: a. manufacturing 200 of an insert comprising the first cellular polymer material, the insert being for example formed by the first portion 20; b. supplying a stiffening reinforcement; c. placing 310 of the insert 20 and the stiffening reinforcement 24 in an injection mold 82 having the shape of the midsole 16, as shown more particularly schematically in FIGS. 15, 16 and 17; d. forming 320, around the insert 20 and the stiffening reinforcement 24, the second portion 22 of the midsole made of cellular polymer material by a molding method.

[0130] The supply step may comprise or consist of the manufacturing of the stiffening reinforcement 24, for example according to the manufacturing method 100 of a stiffening reinforcement 24 as described above or according to another method.

[0131] According to a particularly advantageous embodiment, the step 200 of manufacturing the insert 20 comprising the first cellular polymer material can be carried out by a supercritical fluid foaming process in an autoclave, which is a process known per se to those skilled in the art. Such a foaming process can for example firstly comprise the formation 210 of a primary blank with the first polymer material. This primary blank can for example have a shape that is generally similar, but generally homothetically smaller, than the shape of the insert to be obtained, here therefore of a shape that is similar but homothetically smaller than the shape of the first portion 20 of the midsole 16. This primary blank is for example produced by injection molding of the first polymer material. In this primary blank, the first polymer material is for example in a non-foamed state, or partially foamed. The step 200 of manufacturing the insert can then comprise the placement 220 of the primary blank in an autoclave. In a known manner, an autoclave is an enclosure in which the temperature can in particular be regulated, and in which a pressure and a temperature of a gaseous atmosphere formed by a gas which is introduced into the autoclave can be maintained. The autoclave does not generally have a shape dedicated to the part to be treated, and therefore has an enclosure of dimensions larger than the part to be treated, here the insert. It can be provided that, in this step, several primary blanks are placed simultaneously in the same autoclave to undergo the same supercritical fluid foaming process.Once the autoclave is sealed after placing one or more primary blanks in the autoclave enclosure, the step 200 of manufacturing the insert may comprise the injection 230 of a supercritical fluid into the autoclave and the infusion 240 of the supercritical fluid into the primary blank within the autoclave. The supercritical fluid is for example carbon dioxide CO2, or nitrogen N2. The injection step 230 and infusion 240 are therefore carried out under pressure and temperature conditions for which the fluid is in its supercritical state. The step 200 of manufacturing the insert 20 may then comprise the depressurization 250 of the autoclave transforming the primary blank into an expanded secondary blank, for example by returning to atmospheric pressure. This expanded secondary blank can optionally be used without further processing as an insert for the midsole manufacturing process 300.However, the step 200 of manufacturing the insert 20 may also comprise a shaping step 260, for example by compression molding, by thermo-compression and / or by machining, to obtain the insert intended to form the first portion 20 of the midsole 16. Other steps, in particular heat treatment or relaxation steps, may be provided.

[0132] The production of the insert 20 by a supercritical fluid foaming process in an autoclave makes it possible to obtain an insert made of cellular polymer material having a very low density, while having excellent elasticity properties, that is to say a very high capacity of [insert 20 to quickly return to its initial shape after compression due to support, when the pressure exerted by the sole decreases at the end of the stride. This elasticity allows [insert 20, forming the first portion 20 of the intermediate sole 16, to restore part of the energy which is stored in the insert 20 by the compression and / or the flexion of [insert 20 at the start of the stride.

[0133] However, the insert 20 can be produced by a "steam chest molding" type process, in which expanded beads, therefore already in cellular form, are agglomerated together by surface fusion and adhesion of the beads under the effect of heat provided by steam. In a "steam chest molding" type process, expanded beads of the first cellular polymer material are used. The beads have a diameter which is for example of the order of 1 to 5 millimeters. The beads are introduced and slightly compressed in a mold in the shape of the object to be obtained. Steam is introduced into the mold, under a pressure and a temperature suitable for causing the beads to adhere to each other, by surface fusion of the beads. A "steam chest molding" type process also makes it possible to obtain an insert with a very low density.

[0134] Typically, it will be possible, thanks in particular to the production of the sole in two portionsas described, and by implementing a supercritical fluid foaming process in an autoclave or a “steam chest molding” type process, manufacturing an insert 20 whose density, defined as the mass of the insert 20 (therefore the mass of the first portion 20 of the intermediate sole 16) divided by the volume of the insert 20 (therefore the volume of the first portion 20 of the intermediate sole 16 as defined above) is less than or equal to 0.2 g / cm3, or even less than or equal to 0.1 g / cm3. Preferably, the density of the insert 20 is in the range from 0.05 g / cm3 to 0.1 g / cm3. This density is therefore an average density over the entire insert 20, with local disparities necessarily present due to the techniques for implementing these cellular materials (dispersions between different areas of the insert, skin effects, etc.).Despite such an extremely low density, and therefore despite the relative weakness of the mechanical resistance of the material of the insert 20 which is inherent in such a low density, it is possible to obtain an intermediate sole 16 having the characteristics necessary for the use of the shoe, thanks to the fact that the formation 320 of the second portion 22 of the intermediate sole is carried out by injection / foaming by supercritical fluid around the insert 20, and thanks to the fact that the assembly of the intermediate sole 16 is obtained by at least partial embedding of the first portion 20 in the second portion 22.

[0135] Finally, it is also possible to envisage, for the production of the insert 20, implementing conventional processes for producing midsole, in particular chemical foaming processes. In such a case, it is even possible to envisage producing the insert 20 based on ethylene-vinyl acetate (EVA).

[0136] In a particularly advantageous method, the step 320 of forming the second portion 22 of the midsole is carried out by injection / foaming with supercritical fluid according to a method known per se to those skilled in the art. Thus, this step of forming the second portion of the midsole may comprise a prior step 315 of mixing the second polymer with the supercritical fluid, then the injection 325, into the injection mold 82 in which the insert 20 (and, where appropriate, the stiffening reinforcement 24) are placed, of the mixture of the second polymer with the supercritical fluid. The supercritical fluid is for example carbon dioxide CO2, or nitrogen N2. It may be identical to or different from that which is possibly used in the production of the insert 20. The prior mixing step 315 and the injection step 325 are therefore carried out under pressure and temperature conditions for which the fluid is in its supercritical state.Such a formation 320 of the second portion 22 of the midsole 16, by injection foaming by supercritical fluid, makes it possible to obtain a second portion 22 of the midsole made of cellular material, therefore having good properties for absorbing the mechanical forces of the impact at each stride, presenting good mechanical characteristics of resistance and rigidity, which promotes the stability of the sole, in particular for absorbing the longitudinal and transverse forces during the stride.

[0137] Typically, it will be possible, by implementing a supercritical fluid injection / foaming process, to manufacture, around the insert 20, a second portion 22 of the intermediate sole 16 whose density, defined as the mass of the second portion 22 of the intermediate sole 16 divided by the volume of the second portion 22 of the intermediate sole 16 as defined above, is less than or equal to 0.3 g / cm3, or less than or equal to 0.2 g / cm3. Preferably, the density of the second portion 22 is in the range from 0.1 g / cm3 to 0.2 g / cm3. This density is therefore an average density over the entire second portion 22 of the intermediate sole 16, with local disparities necessarily present due to the techniques for implementing these cellular materials (dispersions between different zones, skin effects, etc.).

[0138] Preferably, the second portion 22 of the midsole 16 has Asker C hardness values in the range of 30 to 55 Asker C, preferably in the range of 35 to 45 Asker C. These hardness values are measured by applying the conditions described in paragraph 7, pages 16 to 20, of the JIS K7312:1996 standard, the hardness values being read after 15 seconds of application of the indenter.

[0139] Preferably, the second portion 22 of the midsole 16 has a split tear strength value greater than 1.5 N / mm, more preferably greater than or equal to 2 N / mm according to standard ISO-20875:2018.

[0140] The method described above for manufacturing an intermediate sole 16 in two portions 20, 22, each of the two portions being made of cellular polymer material, but the two portions having different densities, therefore makes it possible to combine the production of a first portion 20 having good properties of lightness and elasticity, with the production of a second portion 22 of intermediate sole 16 having good mechanical characteristics of strength and rigidity to promote the stability of the sole. In total, the intermediate sole thus produced has an optimum of the characteristics of lightness, elasticity, strength and rigidity.

[0141] The method 300 for manufacturing an intermediate sole 16 which is described above is advantageous in that the assembly of the intermediate sole 16 is obtained without added adhesive, or at least with less added adhesive, by at least partial embedding of the first portion 20, and even more particularly of the stiffening reinforcement 24 when such a stiffening reinforcement 24 is incorporated, in the second portion 22. The absence of glue, or the reduction in the quantity of glue, is particularly advantageous with a view to recycling the sole by avoiding the presence of an additional chemical composition in the assembly, or at least by limiting this presence.The assembly of the midsole 16 by overmolding, as described above, with additional use of glue or without added adhesive, is also very advantageous in the context of the implementation of a stiffening reinforcement 24 comprising an elongated profile of small section, because such a profile has a small useful surface available for possible bonding, so that a bonding operation would be difficult to implement and the bonding force obtained could prove insufficient. In all cases, the reduction or elimination of the use of glue for the assembly of the midsole 16 is beneficial for reducing the disadvantages linked to the use of glue, in particular the cost of the glue, cost and duration of implementation of the glues, release of chemical substances, etc.

[0142] The absence of gluing for the assembly of the midsole 16 also makes it possible to simplify the sole assembly process by eliminating the operation called "stock-fitting". As a result, the use of ovens can be eliminated and consumption reduced. energy and therefore the environmental impact of the process.

[0143] The assembly of the midsole 16 by overmolding, as described above, also promotes the reduction of the number of operators required for the manufacture of the sole, which increases the possibility of production in countries with high labor costs.

[0144] Above all, the assembly of the midsole 16 by overmolding, as described above, allows the creation of new geometries, for example with inserts embedded within the material, a geometry which is impossible to obtain by simple gluing.

[0145] In certain embodiments, it may be provided that the step 310 of placing the insert 20 in an injection mold 82 comprises the placement in the injection mold 82 of at least one outer sole component 18, so that the at least one outer sole component 18 is then assembled to the midsole 16 by forming the second portion 22 by injection molding / supercritical fluid foaming. The assembly of the at least one outer sole component 18 to the midsole 16 is thus obtained at a lower cost, preferably without adding glue.

[0146] In Figures 15, 16, and 17, it is illustrated that it is advantageous to provide that the step 310 of placing the insert 20 and the stiffening reinforcement 24 in an injection mold 82 is carried out with the lower face 26 of the insert forming the first portion 20 of the intermediate sole 16 facing upwards, therefore with the insert 20 vertically upside down. Indeed, this makes it possible to place the stiffening reinforcement 24 quite simply in abutment on the lower face 26 of the insert 20, without it being necessary to provide any particular means for holding the stiffening reinforcement 24 during this step of placement in the injection mold 82. This is particularly true in the case as illustrated for the first embodiment in which the insert 20 comprises in this lower face 26, a recess, here in the form of a groove 21, intended to accommodate at least a portion of the stiffening reinforcement 24.It can therefore be seen that the insert 20 thus comprises the recess 21 whose geometry is complementary to a corresponding part of the stiffening reinforcement 24. When placing the insert 20 and the stiffening reinforcement 24 in the injection mold 82 having the shape of the intermediate sole 16, the corresponding part of the stiffening reinforcement 24 is placed in the recess 21 of the insert 20 to ensure the relative positioning of the insert 20 and the stiffening reinforcement 24 in the injection mold 82.

[0147] Figure 17 also illustrates how to produce an intermediate sole 16, which, as in the first embodiment illustrated in particular in Figures 5, 6 and 7F, comprises a stiffening reinforcement having at least one visible segment 52ea. In this case, the injection mold 82 delimits, around the insert 20, a volume 84 for injection of the second portion 22 of the intermediate sole. It can be seen in Figure 17 that, when the injection mold 82 is closed, the profile 25 of the reinforcement comprises a segment, which will form the visible segment 52ea, which, when the insert 20 and the stiffening reinforcement 24 are placed in the injection mold, extends outside the injection volume 84 of the second portion (22) of the intermediate sole 16, outside of it. In the example, the body of the injection mold 82 therefore comprises a reservation, in a wall of the mold, which accommodates the segment which will form the visible segment 52ea, and which is isolated in such a way sealing of the injection volume 84 so as not to be reached by the mixing of the mixture of the second polymer with the supercritical fluid at the time of injection.

[0148] In addition to the various variants described above, the following examples are described more particularly, which can be implemented independently of the methods described above.

[0149] Example 1: Stiffening reinforcement (24) for a sole (14) of a shoe (10), in particular a sports shoe, of the type in which the stiffening reinforcement (24) comprises at least one elongated profile (25), the profile (25) having a curved guideline which is curved to follow a stiffening reinforcement geometry, of the type in which the stiffening reinforcement (24) extends between a front end (46) and a rear end (48) in a longitudinal direction X, of the type in which the stiffening reinforcement (24) extends transversely between an internal lateral side and an external lateral side in an internal-external transverse direction (Y) perpendicular to the longitudinal direction (X), of the type in which the stiffening reinforcement (24) extends in a height direction (H) perpendicular to the longitudinal (X) and transverse (Y) directions,of the type in which the profile (25) comprises reinforcing fibers embedded in a polymer resin matrix, the curved guideline comprising longitudinal sections (52e, 52i, 54e, 54i) which extend from front to rear, which are offset from each other in the transverse direction (Y), and which are connected by turning sections (56e, 56i, 59, 72, 66e, 66i, 69, 76), of the type comprising at least one front loop (58, 70, 60e, 60i) formed by a front turning section (59, 72, 66e, 66i) connecting the front ends of two successive longitudinal sections along the guideline of the profile (25), of the type comprising at least one rear loop (50i, 50e, 68, 74) formed by a rear turning section (56i, 56e, 69, 76) connecting the rear ends of two successive longitudinal sections along the guideline of the profile.,

[0150] Such a stiffening reinforcement is flexible in flexion around a transverse axis in the metatarsal zone and is capable of restoring, with the least possible losses, the stored flexion energy. Such a stiffening reinforcement makes it possible, for a minimal weight, to optimally distribute the stiffness provided by the stiffening reinforcement over the length of the sole, for example from the heel zone to the metatarsal flexion zone, or even in front of it. In addition, such a geometry of the stiffening reinforcement makes it possible to create stiffness zones, corresponding to each loop, which are at least partly decoupled from each other. In certain variants, such a reinforcement is implemented in an intermediate sole 20 which comprises only a portion and a stiffening reinforcement 24. In the example illustrated, the stiffening reinforcement 24 is integrated into the intermediate sole 16.However, in certain variants, the stiffening reinforcement 24 is distinct from the midsole 16. In such variants, the stiffening reinforcement 24 is for example arranged between the midsole 16 and the outer sole 18, or arranged between the midsole 16 and the upper 12.

[0151] Example 2: Stiffening reinforcement according to example 1, characterized in that the curved guideline of the profile (25) of the stiffening reinforcement (24) is a line closed on itself.

[0152] This is advantageous for limiting a concentration of forces applied by the elongated profile on the cellular material(s) of the midsole which could occur at a free termination and this makes it possible to obtain an increased torsional stiffness of the stiffening reinforcement around a longitudinal axis. In addition, the curved guideline closed on itself makes it possible to obtain an increased torsional stiffness of the stiffening reinforcement around a longitudinal axis.

[0153] Example 3: Stiffening reinforcement according to any one of examples 1 or 2, characterized in that the profile of the stiffening reinforcement comprises: - an external rear loop (56e) formed by an external lateral longitudinal section (52e) and an external central longitudinal section (54e), connected by an external rear turnaround section (56e); - an internal rear loop (50i) formed by an internal lateral longitudinal section (52i) and an internal central longitudinal section (54i), connected by an internal rear turn-over section (56i); - a central front loop (58) which connects the external rear loop to the internal rear loop by being formed by the external central longitudinal section and the internal central longitudinal section, connected by a central front turnaround section.

[0154] Such reinforcement geometry allows in particular to have good stiffness in bending around transverse axes, over the length of the sole, while retaining sufficient flexibility in torsion around a longitudinal axis, in particular in a rear part of the sole, to accompany the pronation / supination movements of the foot.

[0155] Example 4: Stiffening reinforcement according to example 3, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the central front turning section (59) extends in front of the arch line (LA).

[0156] This creates a central front loop that extends forward to stiffen this part of the sole, particularly in the metatarsal flexion area.

[0157] Example 5: Stiffening reinforcement according to example 4, characterized in that the stiffening reinforcement (24) has, in front of the arch line (LA), a line of maximum transverse width of the stiffening reinforcement in front of the arch line, called the metatarsal line (LM), and in that the central front turning section (59) extends in front of the metatarsal line (LM).

[0158] This creates a central front loop that extends forward to stiffen this part of the sole, right up to the area of the phalanges of the foot.

[0159] Example 6: Stiffening reinforcement according to any one of examples 3 to 5, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the external rear turn-over section (56e) and the internal rear turn-over section (56i) extend behind the arch line (LA).

[0160] This creates a rear loop that extends forward to stiffen this part of the sole, preferably in the heel area.

[0161] Example 7: Stiffening reinforcement according to any one of examples 3 to 6, characterized in that the profile (25) of the stiffening reinforcement (24) comprises a peripheral front loop (70) which is formed by the external lateral longitudinal section (52e) and the internal lateral longitudinal section (521), connected by a peripheral front turn-over section (72).

[0162] Such a peripheral loop makes it possible to maintain a link between the lateral and medial stiffening reinforcement parts, like an anti-roll bar in motor vehicle suspensions, to better control the pronation / supination movements of the foot.

[0163] Example 8: Stiffening reinforcement according to any one of examples 3 to 7, characterized in that the curved guideline is a line closed on itself, and in that the curved guideline closed on itself comprises as only turning sections the external rear turning section (56e), the internal rear turning section (56i), the central front turning section (59) and the peripheral front turning section (72).

[0164] Such geometry allows for a relatively simple geometry reinforcement with limited weight.

[0165] Example 9: Stiffening reinforcement according to any one of examples 3 to 8, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the stiffening reinforcement (24) comprises a heel zone, behind the arch line (LA), in which the external lateral longitudinal section (52e) is arranged at a higher level than the external central longitudinal section (54e) in the height direction (Z).

[0166] Such geometry allows to stabilize the heel area well, especially in the transverse direction on the external lateral side, while maintaining maximum cushioning in the part of the sole which is transversely in the center directly under the heel.

[0167] Example 10: Stiffening reinforcement according to any one of examples 3 to 9, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the stiffening reinforcement (24) comprises a heel zone, behind the arch line (LA), in which the internal lateral longitudinal section (52i) is arranged at a higher level than the internal central longitudinal section (54I) in the height direction (Z).

[0168] Such geometry allows to stabilize the heel area well, especially in the transverse direction on the internal lateral side, while maintaining maximum cushioning in the part of the sole which is transversely in the center directly under the heel.

[0169] Example 11: Stiffening reinforcement according to any one of examples 3 to 10, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the stiffening reinforcement dification (24) comprises a heel zone, behind the arch line (LA), in which the external lateral longitudinal section (52e) is arranged at a higher level than the internal lateral longitudinal section (521) in the height direction (Z).

[0170] Example 12: Stiffening reinforcement according to one of examples 1 or 2, characterized in that the profile (25) of the stiffening reinforcement comprises: - an external front loop (60e) formed by an external lateral longitudinal section (52e) and an external central longitudinal section (54e), connected by an external front turnaround section (66e); - an internal front loop (60I) formed by an internal lateral longitudinal section (52i) and an internal central longitudinal section (54i), connected by an internal front turning section (66i); - a central rear loop (68) which connects the external front loop (60e) to the internal front loop (60i) by being formed by the external central longitudinal section (54e) and the internal central longitudinal section (54I), connected by a central rear turnaround section (69).

[0171] Such reinforcement geometry allows in particular to have good stiffness in bending around transverse axes, over the length of the sole, while retaining sufficient flexibility in torsion around a longitudinal axis, in particular in a front part of the sole, to accompany the pronation / supination movements of the foot.

[0172] Example 13: Stiffening reinforcement according to any one of the preceding examples, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that the stiffening reinforcement (24) comprises a transverse tilting zone (ZB) arranged in front of the arch line (LA), each longitudinal section (52e, 52I, 54e, 54I) comprising, in the tilting zone (ZB), an inflection point curved upwards at a low point in the height direction (Z).

[0173] Example 14: Stiffening reinforcement according to example 13, characterized in that the stiffening reinforcement (24) has, in front of the arch line (LA), a line of maximum transverse width of the stiffening reinforcement in front of the arch line, called the metatarsal line (LM), and in that the rocking zone (ZB) is arranged behind the metatarsal line (LM) or at the level of the metatarsal line (LM).

[0174] Such a tilting zone encourages a general tilting forward of the user's body, benefiting the dynamism of the user's running.

[0175] Example 15: Stiffening reinforcement according to any one of the preceding examples, characterized in that the stiffening reinforcement (54) is at least partly embedded in an intermediate sole (16) of the sole, the intermediate sole being made of one or more cellular polymer materials.

[0176] This ensures reliable assembly of the reinforcement in the midsole, this assembly being obtained with a reduced number of operations, possibly without adhesive.

[0177] Example 16: Stiffening reinforcement according to example 15, characterized in that the profile (25) has at least one visible segment (52e) outside the midsole (16).

[0178] Example 17: Stiffening reinforcement according to example 16, characterized in that an empty space (78) is provided between the visible segment (52ea) of the profile (25) of the stiffening reinforcement (24) and a lateral face of the intermediate sole (16).

[0179] In this case, the risk of tearing that could occur at an interface where the visible segment would be in contact with the midsole without being embedded inside it is avoided.

[0180] Example 18: Stiffening reinforcement according to any one of the preceding examples, characterized in that the stiffening reinforcement (24) has a line of minimum transverse width of the stiffening reinforcement, called the arch line (LA), and in that, in front of the arch line (LA), the elongated profile (25) of the stiffening reinforcement (24) has, in section through any plane containing the transverse and height directions, a section having a transverse width greater than its height in the height direction.

[0181] With such a flattened section, the stiffening reinforcement is allowed to flex in the metatarsal flexion zone, with a desired stiffness.

[0182] Example 19: A stiffening reinforcement according to any one of Examples 3 to 10, characterized in that the reinforcing fibers in the profile of the stiffening reinforcement comprise reinforcing fibers oriented in the direction of the curved guideline within the resin matrix which are continuous fibers along the length of the curved guideline.

[0183] The use of continuous fibers makes it possible to optimize the bending stiffness of the profile, for a given weight.

[0184] Example 20: Stiffening reinforcement according to any one of the preceding examples, characterized in that the reinforcing fibers comprise carbon, glass, and / or aramid fibers.

[0185] Carbon, glass, and / or aramid fibers allow the flexural stiffness of the profile to be optimized for a given weight.

[0186] Example 21: Stiffening reinforcement according to any one of the preceding examples, characterized in that the polymer resin of the stiffening reinforcement is a thermoplastic polymer resin.

[0187] This allows easy shaping of the profile.

[0188] Example 22: Method (100) for manufacturing a stiffening reinforcement according to any one of the preceding examples, characterized in that the method comprises: i) manufacturing, in particular by pultrusion, an elongated profile (25) comprising reinforcing fibers, in particular continuous fibers, embedded in a thermoplastic polymer resin matrix; ii) heating (120) the elongated profile (25) to bring it into a plastic state, and curving (130) the elongated profile (25), in the plastic state, to bend the guideline of the profile so that it follows the stiffening reinforcement geometry.

[0189] Example 23: Manufacturing method (100) according to example 22, characterized in that the method comprises a step (140) of local shaping of the section of the elongated profile in its plastic state to give it, locally, a section having a transverse width greater than its height in the height direction.

[0190] Example 24: Sole (14) of a shoe (10), in particular a sports shoe, characterized in that the sole comprises a stiffening reinforcement (24) according to any one of examples 1 to 21 and / or manufactured using the method according to any one of examples 22 to 23.

[0191] Example 25: Sole (14) of a shoe (10), in particular a sports shoe, comprising an intermediate sole (16) comprising a first portion (20) made of a first cellular polymer material and having a first density, and comprising a second portion (22) made of a cellular polymer material and having a second density greater than the first density, characterized in that the sole comprises a stiffening reinforcement according to any one of examples 1 to 21, and in that the second portion (22) is overmolded around the first portion (20) and the stiffening reinforcement (24) so as to ensure the assembly of the intermediate sole (16) by at least partial coating of the first portion (20) and the stiffening reinforcement (24) in the second portion (22).

[0192] Example 26: Shoe (10), in particular a sports shoe, characterized in that it comprises a shoe sole (14) according to any one of examples 24 or 25.

[0193] Among the various variants described above, there is described more particularly a stiffening reinforcement 24 for a shoe sole 24, a. of the type in which the stiffening reinforcement 24 comprises an elongated profile 25, the profile 25 having a curved guideline which is curved to follow a stiffening reinforcement geometry, b. of the type in which the stiffening reinforcement 24 extends between a front end 46 and a rear end 48 in a longitudinal direction X of the sole, c. of the type in which the stiffening reinforcement 24 extends transversely between an internal lateral side and an external lateral side in an internal-external transverse direction Y perpendicular to the longitudinal direction X, d. of the type in which the stiffening reinforcement 24 extends in a height direction Z perpendicular to the longitudinal directions X and transverse directions Y, e.of the type in which the profile 25 comprises reinforcing fibers embedded in a polymer resin matrix, the stiffening reinforcing fibers being oriented in the direction of the curved guideline within the resin matrix, the curved guideline comprising longitudinal sections 52e, 52i, 54e, 54i which extend from front to rear, which are offset from each other in the transverse direction Y, and which are connected by turn-over sections, f. of the type comprising at least one front loop formed from a turn-over section. front connecting the front ends of two successive longitudinal sections along the guideline of the profile, g. of the type comprising at least one rear loop formed by a rear turn-over section connecting the rear ends of two successive longitudinal sections along the guideline of the profile, the stiffening reinforcement 24 being characterized in that it comprises I. an external rear loop 50e formed by an external lateral longitudinal section 52e and an external central longitudinal section 54e, connected by an external rear turn-around section 56e; 11. an internal rear loop 501 formed by an internal lateral longitudinal section 52i and an internal central longitudinal section 54i, connected by an internal rear turn-around section 56i; 11. a central front loop 58 which connects the external rear loop 50e to the internal rear loop 50i by being formed by the external central longitudinal section 54e and the internal central longitudinal section 54i, connected by a central front turn-around section 59.

[0194] The advantages of such reinforcement have been described above, in particular due to the fact that the internal 50i and external 50e rear loops of the stiffening reinforcement 24 are free relative to each other in a rear part of the sole, in the transverse direction Y and in the height direction Z.

[0195] Among the various variants described above, there is also described more particularly a stiffening reinforcement 24 for a sole 14 of a shoe 10, of the type in which the stiffening reinforcement 24 comprises an elongated profile 25, the profile 25 having a curved guideline which is curved to follow a stiffening reinforcement geometry, a. of the type in which the stiffening reinforcement 24 extends between a front end 46 and a rear end 48 in a longitudinal direction X, b. of the type in which the stiffening reinforcement extends transversely between an internal lateral side and an external lateral side in an internal-external transverse direction Y perpendicular to the longitudinal direction X, c. of the type in which the stiffening reinforcement 24 extends in a height direction Z perpendicular to the longitudinal directions X and transverse directions Y, d.of the type in which the profile 25 comprises reinforcing fibers embedded in a polymer resin matrix, the stiffening reinforcing fibers being oriented in the direction of the curved guideline within the resin matrix, the curved guideline comprising longitudinal sections 52e, 52I, 54e, 54I which extend from front to rear, which are offset from each other in the transverse direction, and which are connected by turning sections, e. of the type in which the profile 25 comprises at least one front loop 58, 70, 60e, 60i formed by a front turning section 59, 72, 66e, 66i connecting the front ends of two successive longitudinal sections along the guideline of the profile, f.of the type in which the profile comprises at least one rear loop 50i, 50e, 68, 74 formed of a rear turning section 56i, 56e, 69, 76 connecting the rear ends of two successive longitudinal sections along the guideline of the profile, g. characterized in that the curved guideline of the stiffening reinforcement profile is a line closed on itself.

Claims

Claims 1. Method (300) for manufacturing an intermediate sole (16) for a sole (14) of a shoe (10), in particular for a sports shoe, the intermediate sole comprising a first portion (20) made of a first cellular polymer material, comprising a stiffening reinforcement (24), and comprising a second portion (22) made of a second cellular polymer material, characterized in that the method comprises the steps of: - manufacturing (200) an insert (20) comprising the first cellular polymer material; - placing (310) the insert (20) in an injection mold (82) having the shape of the midsole (16); - formation (320), around the insert (20), of the second portion (22) of the midsole (16) made of cellular polymer material by a supercritical fluid injection / foaming molding process.

2. Manufacturing method according to claim 1, characterized in that the step of forming the second portion (22) of the intermediate sole (16) comprises a prior step of mixing the second polymer with the supercritical fluid, then injecting, into the injection mold (82), the mixture of the second polymer with the supercritical fluid.

3. Manufacturing method according to any one of claims 1 or 2, characterized in that the step of manufacturing (200) the insert (20) comprising the first cellular polymer material is carried out by foaming by supercritical fluid in an autoclave comprising the formation (210) of a primary blank with the first polymer material, the placement (220) of the primary blank in an autoclave, the injection (230) of a supercritical fluid into the autoclave and the infusion (240) of the supercritical fluid into the primary blank within the autoclave, the depressurization (250) of the autoclave transforming the primary blank into an expanded secondary blank.

4. Manufacturing method according to claim 3, characterized in that the step (200) of manufacturing the insert comprises a step (260) of shaping the insert (20) from the secondary blank, for example by compression molding, to obtain the insert (20).

5. Manufacturing method according to any one of the preceding claims, characterized in that the assembly of the intermediate sole (16) is obtained without added adhesive by at least partial embedding of the first portion (20) in the second portion (22).

6. Manufacturing method according to any one of the preceding claims, characterized in that the first portion (20) of the intermediate sole (16) has a first density, and the second portion (22) of the intermediate sole (16) has a second density greater than the first density.

7. Manufacturing method according to any one of the preceding claims, characterized in that the step of placing (310) the insert (20) in an injection mold (82) also comprises the placement of at least one outer sole component (18), and in that the at least one outer sole component (18) is assembled to the midsole (16) by forming the second portion (22) by injection molding / supercritical fluid foaming.

8. Manufacturing method according to any one of the preceding claims, characterized in that the method also comprises, before the step of forming the second portion (22) of the midsole (16), a step of supplying a stiffening reinforcement (24), in that the step of placing the insert (20) in the injection mold (82) also comprises placing the stiffening reinforcement (24) in the injection mold (82), and in that the step of forming the second portion (22) of the midsole (16) comprises forming (320), around the insert (20) of the stiffening reinforcement (24), the second portion (22) of the midsole (16) made of cellular polymer material by the supercritical fluid injection molding / foaming process.

9. Manufacturing method according to claim 8, characterized in that the stiffening reinforcement (24) is made of composite material comprising reinforcing fibers embedded in a polymer resin.

10. Manufacturing method according to any one of claims 8 or 9, characterized in that the stiffening reinforcement (24) comprises an elongated profile (25), the profile having a curved guideline which is curved to follow a stiffening reinforcement geometry.

11. Manufacturing method according to any one of claims 8 to 10, characterized in that the assembly of the intermediate sole (16) is obtained without added adhesive, by at least partial embedding of the first portion (20) and of the stiffening reinforcement (24) in the second portion (22).

12. Manufacturing method according to any one of claims 8 to 11, characterized in that the insert (20) comprises a recess (21) whose geometry is complementary to a corresponding part of the stiffening reinforcement (24), and in that, when placing the insert (20) and the stiffening reinforcement (24) in the injection mold (82) having the shape of the intermediate sole (16), the corresponding part of the stiffening reinforcement (24) is placed in the recess (21) of the insert (20) to ensure the relative positioning of the insert (20) and the stiffening reinforcement (24) in the injection mold (82).

13. Sole (14) of a shoe (10), in particular for a sports shoe, comprising an intermediate sole (16) comprising a first portion (20) made of a first cellular polymer material and having a first density, and comprising a second portion (22) made of cellular polymer material and having a second density greater than the first density, characterized in that the second portion (22) is overmolded around the first portion (20) so as to ensure the assembly of the intermediate sole (16) by at least partial coating of the first portion (20) in the second portion (22).

14. Shoe sole according to claim 13, characterized in that the second portion (22) covers a lower face (26) and lateral faces (28) of the first portion (20), but leaves an upper face (30) of the first portion (20) visible.

15. Shoe sole according to any one of claims 13 or 14, characterized in that it comprises a stiffening reinforcement (24), in that the second portion (22) is overmolded around the first portion (20) and the stiffening reinforcement (24) so as to ensure the assembly of the intermediate sole (16) by at least partial coating of the first portion (20) and the stiffening reinforcement (24) in the second portion (22), and in that the stiffening reinforcement (24) comprises an elongated profile (25), the profile having a curved guideline which is curved to follow a stiffening reinforcement geometry.

16. Shoe sole according to claim 15, characterized in that it extends between a front end and a rear end in a sole longitudinal direction (14), in that it extends transversely between an internal lateral side and an external lateral side in an internal-external transverse direction perpendicular to the longitudinal direction, in that it extends in a height direction perpendicular to the longitudinal and transverse directions, and in that the curved guideline of the profile (25) comprises longitudinal sections (52e, 52I, 54e, 54I) which extend from front to rear, which are offset from each other in the transverse direction, and which are connected by turning sections (56e, 56i, 59, 72, 66e, 66i, 69, 76), the profile of the reinforcement comprising at least one front loop (58, 70, 60th, 60th) formed from a front turnaround section (59, 72, 66th,66I) connecting the front ends of two successive longitudinal sections along the guideline of the profile, and at least one rear loop (50I, 50e, 68, 74) formed from a rear turning section (56I, 56e, 69, 76) connecting the rear ends of two successive longitudinal sections along the guideline of the profile (25)., 17. Shoe sole according to claim 16, characterized in that the profile (25) of the stiffening reinforcement (24) comprises: - an external rear loop (50e) formed by an external lateral longitudinal section (52e) and an external central longitudinal section (54e), connected by an external rear turnaround section (56e); - an internal rear loop (50i) formed by an internal lateral longitudinal section (52i) and an internal central longitudinal section (54i), connected by an internal rear turn-over section (56i); - a central front loop (58) which connects the external rear loop (50e) to the internal rear loop (50I) by being formed by the external central longitudinal section (54e) and the internal central longitudinal section (54i), connected by a central front turnaround section (59).

18. Shoe sole according to one of claims 16 or 17, characterized in that the profile (25) of the stiffening reinforcement (24) comprises a peripheral front loop (70) which is formed by the external lateral longitudinal section (52e) and the internal lateral longitudinal section (52i), connected by a peripheral front turn-up section (72).

19. Shoe sole according to any one of claims 15 to 18, characterized in that the curved guideline of the profile of the stiffening reinforcement is a line closed on itself.

20. Shoe sole according to any one of claims 15 to 19, characterized in that, in a front longitudinal half of the sole, the stiffening reinforcement is arranged between a lower face of the first portion of the intermediate sole and an upper face of the second portion of the intermediate sole.

21. Shoe sole according to any one of claims 18 to 20, characterized in that the stiffening reinforcement (24) comprises a visible segment outside the intermediate sole (16).

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