Sole structure for item of footwear

Abstract

The invention relates to a sole structure comprising a midsole (1) having two respectively front (9a) and rear (9b) surfaces and two respectively lateral (9c) and medial (9d) surfaces, and also a sheet (4) having two respectively front (4a) and rear (4b) portions arranged opposite the front (9a) and rear (9b) surfaces, respectively, of the midsole and two respectively lateral (4c) and medial (4d) portions arranged opposite the lateral (9c) and medial (9d) surfaces, respectively, the lateral (4c) and medial (4d) portions being formed by a respective branch (13a, 13b) which extends longitudinally from the front portion (4a) while forming between them a through-slot (14), and having different lengths such that only the long branch (13a) extends continuously to the rear to form the rear portion (4b) on its rear end (17), the slot (14) extending on the rear surface (9b).

Description

[0001] DESCRIPTION

[0002] Title: Sole structure for footwear

[0003] The invention relates to a sole structure for a footwear article, as well as a footwear article comprising such a sole structure surmounted by an upper to form a space for receiving a user's foot.

[0004] It applies in particular to footwear intended for the practice of a sporting and / or leisure activity, especially running.

[0005] We know of structures which include a lower sole, called the wear sole, designed to come into contact with the ground, as well as an intermediate sole arranged to cushion impacts on the ground and limit their transmission to the user.

[0006] In the context of practicing a high-impact sporting activity, such as running on hard surfaces like track or road, it is known to use structures with a midsole made of a cellular polymer material.

[0007] These materials allow the midsole to absorb, through elastic compression, the shocks produced by the impacts of the foot on the ground to limit the risk of injury to the user, and then to return, through elastic rebound, the energy generated by said deformation when said foot lifts off the ground, in order to provide a rebound effect to improve the stride of said user.

[0008] These materials also have the advantage of being lightweight, which helps to keep the overall weight of the footwear unaffected.

[0009] To further improve the stride, document EP-3355738 provides for a sole structure incorporating a stiffening plate associated with the midsole to increase its flexural rigidity, particularly along a longitudinal direction parallel to the maximum dimension of the user's foot, which allows for an additional rebound effect to be provided to said foot during its propulsion phase relative to the ground, by transmitting forces from the front to the back of said foot.

[0010] In particular, the unfolding of the foot is composed of a set of efforts following the cycle time (flexion, relaxation, eversion) which causes the plate to flex longitudinally, particularly at the level of an area located opposite the metatarsophalangeal joints of said foot, in order to be able to restore the energy stored during this flexion during the propulsion phase of said foot.

[0011] However, plates designed according to prior art, particularly in that they extend longitudinally and transversely under virtually the entire foot, can be excessively rigid. Specifically, the transverse rigidity of the plates causes discomfort without significantly contributing to the proper gait of the foot.

[0012] The invention aims to improve the prior art by proposing a sole structure whose longitudinal and transverse flexural stiffness is arranged to improve a user's stride, while limiting weight and optimizing user comfort.

[0013] To this end, according to a first aspect, the invention proposes a sole structure for a footwear article comprising an intermediate sole made of alveolar polymer material, said intermediate sole having two surfaces respectively front and rear along a longitudinal direction and two surfaces respectively lateral and medial along a transverse direction, said sole structure further comprising a stiffening plate, said plate having two portions respectively front and rear arranged opposite the front and rear surfaces of the intermediate sole and two portions respectively lateral and medial arranged opposite the lateral and medial surfaces of the intermediate sole, the lateral and medial portions being formed respectively by a branch which extends longitudinally from the front portion forming between them a through-hole,said branches being of different lengths such that only the longest branch extends continuously backwards to form the rear portion on the rear end of said branch, the light extending onto the rear surface.

[0014] According to a second aspect, the invention proposes a footwear article comprising such a sole structure and an upper mounted on said structure, forming with it a space for receiving a user's foot.

[0015] Other features and advantages of the invention will become apparent in the following description, made with reference to the accompanying figures, in which:

[0016] [Fig.1] represents, in exploded perspective, a sole structure according to one embodiment of the invention;

[0017] [Fig.2] represents a view from below of the intermediate sole of the sole structure of figure 1;

[0018] [Fig.3a]

[0019] [Fig.3b],

[0020] [Fig. 3c] and

[0021] [Fig.3d] each represent the stiffening plate equipping the base structure of figure 1, respectively in perspective view from above (figure 3a), in perspective view from below (figure 3b), in top view (figure 3c) and in side view (figure 3d).

[0022] In relation to these figures, a sole structure for a footwear item, particularly intended for the practice of a sporting and / or leisure activity such as running, is described below, as well as a footwear item equipped with such a structure.

[0023] The footwear item comprises an upper (not shown) which is mounted on the sole structure, forming a space to accommodate a user's foot. The upper can be made of natural leather (smooth, nubuck, suede, etc.) or synthetic leather (imitation leather), or even polymer material (mesh, nylon, etc.). In particular, the upper can be formed by assembling, notably by stitching, several textile pieces together. These pieces can also be made of materials with different compositions, appearances, and / or properties, for example, depending on their relative position with respect to the user's foot, the desired properties in each location (reinforcement at the instep for lacing, etc.), or the overall aesthetic appearance desired for the item.

[0024] To allow its mounting on the sole structure, the upper includes a lower edge which can be fixed to said sole structure, in particular by gluing and / or sewing.

[0025] In the description, terms relating to positioning in space are used with reference to the sole structure as shown in the figures, and specifically in relation to its position under the user's foot. Thus:

[0026] - the terms "front" and "back" refer to arrangements that are close to the front and back of the foot respectively, and located on the left and right respectively in Figure 1;

[0027] - the term "longitudinal" refers to a direction extending in a vertical plane that is parallel to a maximum dimension of the footing structure, measured between its front and rear ends, and the term "transverse" refers to a direction extending in a vertical plane that is perpendicular to this longitudinal plane;

[0028] - the terms "length" and "width" refer to dimensions measured along a longitudinal and transverse direction respectively, as defined previously;

[0029] - the terms "lateral" and "medial" refer to arrangements close to the lateral and medial parts of the foot respectively.

[0030] The sole structure is specifically designed for the manufacture of footwear suitable for high-impact sports activities, such as running on hard surfaces (road, track), and more particularly for activities such as speed training, competitions and / or long-distance running over medium or long distances (half-marathons, marathons...).

[0031] To achieve this, the sole structure includes a midsole 1 which is made of a cellular polymer material, in particular a flexible polymer foam.

[0032] This material gives the midsole 1 sufficient flexibility and elasticity to allow it to absorb the shocks produced by the impacts of the foot on the ground, and then to return to said foot the energy accumulated during an impact at the moment of propulsion of said foot, that is to say when said foot lifts off said ground, in order to provide said foot with a rebound effect to improve the stride of the user.

[0033] The midsole 1 can be made from polyurethane (PU) foam or polyether, particularly polyether block amide. These materials, in addition to offering good elasticity, also have the advantage of reduced weight, resulting in a lighter shoe that provides optimal comfort for the user, notably by limiting energy loss during speed training and / or competitions.

[0034] In relation to Figure 1, the midsole 1 comprises two blocks respectively upper 1a and lower 1b which are each made of a cellular polymer material.

[0035] The upper block 1a and lower block 1b can be made of cellular polymer materials with different physical and / or mechanical properties, particularly in terms of density. In particular, the lower block 1b can have a higher initial density to absorb shocks from impacts on the ground, and thus guarantee a good lifespan for the base structure.

[0036] Conversely, the upper block 1a may have a reduced density, in order to present greater lightness and elasticity for the user's comfort, as well as for the return to the user's foot of the energy generated by the shock absorption by the lower block 1b.

[0037] The structure shown further includes an outsole 2 which is fixed under the midsole 1, and in particular by gluing to an underside 3 of the lower block 1 b, in order to come into contact with the ground when using the footwear.

[0038] The outsole 2 comprises several inserts 2a each fixed to a portion of the underside 3, and made of a material suitable for resisting abrasion and for facilitating the grip of the footwear on the ground.

[0039] The structure also includes a stiffening plate 4 which is associated with the midsole 1 to increase its flexural stiffness along a longitudinal direction, particularly in a region located at the metatarsophalangeal joints of the foot.

[0040] This arrangement allows the sole structure to store energy during the flexion of the phalanges, in order to return this energy to the foot during its propulsion phase.

[0041] In the embodiment shown, plate 4 is positioned between the upper block 1a and the lower block 1b of the midsole 1. In the figures, the lower block 1b is overmolded onto the upper block 1a, beneath which plate 4 is positioned. The midsole 1 can be manufactured using a process that successively involves:

[0042] - produce the upper block 1a, for example by injection and molding of a first precursor polymeric and alveolar material in a first molding cavity provided for this purpose;

[0043] - to attach by gluing the stiffening plate 4 under a lower face 5 of said upper block;

[0044] - place the upper block assembly 1a / stiffening plate 4 in a second molding cavity;

[0045] - inject into said second molding cavity a second alveolar polymer precursor material, in order to overmold the lower block 1b on said upper block, so as to place said plate between said blocks.

[0046] In particular, the upper block 1a may include on its lower face 5 an impression of complementary shape to that of the stiffening plate 4, in order to allow the association of said plate to said upper block by gluing in said complementary impression.

[0047] In Figure 1, the lower block 1b is overmolded to surround the peripheral edges 6 of the upper block 1a, so that only the upper face 7 of said upper block remains visible after said overmolding. Thus, the lower block 1b forms a recess 8 in which the upper block 1a / plate 4 assembly is placed, said plate resting on a base 9 of said recess.

[0048] To create the footwear, the lower edge of an upper can be fixed to the peripheral edges 10 of the housing 8, in order to form a space for the foot to be received with the upper face 7 of the upper block 1a. In addition, a so-called insole can be placed in the space, in particular in a removable manner, in order to improve comfort and hygiene for the user when putting on the item.

[0049] The stiffening plate 4 is formed of a composite material, in particular based on a polymer resin, which includes stiffening fibers, in particular carbon, glass and / or aramid fibers. The lower face 5 of the upper block 1a and the bottom 9 of the lower block 1b each have two surfaces respectively front 9a and rear 9b in a longitudinal direction, as well as two surfaces respectively lateral 9c and medial 9d in a transverse direction.

[0050] Similarly, plate 4 has two portions respectively front 4a and rear 4b, arranged opposite the respective front surfaces 9a and rear 9b of blocks 1a, 1b, as well as two portions respectively lateral 4c and medial 4d, arranged opposite the respective lateral surfaces 9c and medial 9d of said blocks.

[0051] Advantageously, plate 4 has a length that is between 80% and 95% of the length of the midsole 1, so that it can extend lengthwise over the majority of the user's foot, and thus allow the energy stored in flexion from the front of said foot to the heel during the propulsion phase of said foot.

[0052] For this purpose, the front portion 4a of the plate 4 is intended to be positioned opposite a phalangeal region 11 of the midsole 1. Similarly, the rear portion 4b of the plate 4 is intended to be positioned at least partially opposite a heel region 12 of the midsole 1.

[0053] The lateral portions 4c and medial 4d of plate 4 are formed by respectively a branch 13a, 13b which extends longitudinally from the front portion 4a, forming between them a through-hole 14.

[0054] The presence of the slot 14 in the forefoot region helps limit lateral forces on the foot during pronation, particularly when the user flexes their foot at the metatarsophalangeal joints. Specifically, slot 14 provides greater flexibility to the front of plate 4 in the transverse direction. With this arrangement, the forces exerted by the deformation of the midsole 1 are distributed primarily along a longitudinal direction, with minimal losses in the transverse direction during pronation, thus returning an optimal amount of energy to the foot during the propulsion phase.

[0055] In the embodiment shown, the lower block 1b has a lower cavity 15 which can be formed during its overmolding under the plate 4, notably by means of an additional projection formed for this purpose in the second molding cavity of said lower block. Advantageously, the lower cavity 15 opens into the opening 14, in order to prevent possible damage to the plate 4 from contact with the ground during sporting activity.

[0056] The branches 13a, 13b have different lengths, so that only the long branch 13a extends continuously towards the rear, so as to form the rear portion 4b on the rear end 17 of said long branch, the light further propagating on the rear surfaces 9b of the midsole 1.

[0057] This arrangement allows plate 4 to extend continuously from the front to the back of the midsole 1 to achieve the desired longitudinal flexural behavior. Furthermore, a lighter stiffening plate 4 is obtained, weighing approximately 15g, thus reducing the overall weight of the footwear, while still benefiting, thanks to the long arm 13a, from sufficient flexural stiffness to ensure that forces are distributed across the entire longitudinal dimension of the midsole 1.

[0058] In the embodiment shown, the long branch 13a is the lateral branch. Indeed, during a stride, the foot pronates against the ground primarily at its lateral edge, where the arch of the plantar fascia is less pronounced. Furthermore, the short branch 13b, which is therefore the medial branch, has a length that is approximately 20% to 50% of the length of the long branch 13a. Alternatively, the long branch could be the medial branch 13b.

[0059] According to one embodiment, the light 14 has a length which is between 65% and 85% of the total length of the plate 4. In particular, the length of the light 14 is measured from the rear end 17 of the long branch 13a, to which said light extends.

[0060] Similarly, the opening 14 has a maximum width, in the front portion 4a of the plate 4, which is between 20% and 30% of the total width of said front portion. In the embodiment shown, the opening has a tapered shape in the front portion 4a that converges longitudinally from a rear end 16 of the short arm 13b, the maximum width of said opening being measured at said rear end.

[0061] For example, for a French shoe size "43", plate 4 shows:

[0062] - a total length of approximately 232 millimeters, light 14 having a length between 185 and 186 millimeters;

[0063] - a front portion 4a with a total width of approximately 88 millimeters, the opening 14 having a maximum width of approximately 19 millimeters.

[0064] In relation to the figures, plate 4 has a forefoot region 18 which extends longitudinally over between 20% and 30% of the total length of said plate. These dimensions allow the forefoot region 18 to extend opposite a phalangeal region 11 of the midsole 1.

[0065] The forefoot region 18 has a U-shaped geometry, the base of which forms the anterior portion 4a, extending longitudinally opposite the anterior joints of the phalanges of the foot. Furthermore, two anterior segments 19a and 19b, each from a branch 13a and 13b respectively, extend longitudinally from the base of the U. Advantageously, the plate 4 has a curved geometry, at least in its forefoot region 18, by positioning the anterior edge 20 of said region above its posterior edge 21. This arrangement reduces mechanical stress on the plantar flexion muscles, thereby improving foot propulsion.

[0066] In relation to the figures, and in particular figures 1, 3a, 3b and 3d, the forefoot region 18 shows a difference in height between its front edge 20 and rear edge 21 which is greater than 10%, and in particular of the order of 20% of the total length of the plate 4.

[0067] Moreover, as shown in more detail in figure 3d, the forefoot region 18 has different radii of curvature along the longitudinal direction.

[0068] Each branch 13a, 13b also presents an intermediate segment 22a, 22b which extends at least partially opposite a metatarsophalangeal region 23 of the intermediate sole 1.

[0069] Advantageously, the intermediate segments 22a, 22b also have a curvature between their respective front edges 24a, 24b and a low point 25 of the plate 4, in order to facilitate propulsion of the foot without additional strain on the muscles of the plantar arch.

[0070] In particular, the lower point 25 of plate 4 is arranged to be positioned opposite the metatarsophalangeal joints of the foot when using the footwear.

[0071] In the embodiment shown, the intermediate segments 22a and 22b each extend longitudinally over between 8% and 15% of the total length of plate 4. The intermediate segment 22a of the lateral long branch 13a has a length that is greater than the length of the intermediate segment 22b of the medial branch 13b. In particular, the lateral branch 13a has a length that is between 200% and 220% of the length of the medial branch 13b.

[0072] Furthermore, the medial branch 13b is formed solely from an anterior segment 19b and an intermediate segment 22b as described previously, the posterior border 26 of its intermediate segment 22b forming the free end 16 of said medial branch. In particular, the free end 16 is formed at the lower point 25 of plate 4.

[0073] Thus, only the long lateral branch 13a has a rear segment 27 which extends opposite a midfoot region 28, and at least partially opposite a heel region 12 of the midsole 1.

[0074] In the figures, the rear segment 27 extends longitudinally over between 40% and 80% of the longitudinal dimension of the heel region 12 of the midsole 1. Furthermore, the rear portion 4b of the plate 4, which is formed on the rear segment 27, has a maximum width which is between 40% and 60% of the maximum width of said plate.

[0075] The rear segment 27 further presents a rear area 29 which is substantially flat, said rear area being connected longitudinally to the rear end 30 of the lateral intermediate segment by a front area 31 which is curved upwards from said intermediate segment towards said rear area.

Claims

DEMANDS 1. Sole structure for a footwear article comprising an intermediate sole (1) made of cellular polymer material, said intermediate sole having two surfaces respectively front (9a) and rear (9b) in a longitudinal direction and two surfaces respectively lateral (9c) and medial (9d) in a transverse direction, said sole structure further comprising a stiffening plate (4), said plate having two portions respectively front (4a) and rear (4b) arranged opposite the front (9a) and rear (9b) surfaces of the intermediate sole and two portions respectively lateral (4c) and medial (4d) arranged opposite the lateral (9c) and medial (9d) surfaces of the intermediate sole (1), said sole structure being characterized in that the lateral (4c) and medial (4d) portions are formed respectively by a branch (13a,13b) which extends longitudinally from the front portion (4a) forming between them a through-hole (14), said branches having different lengths so that only the long branch (13a) extends continuously towards the rear to form the rear portion (4b) on the rear end (17) of said branch, the hole (14) extending onto the rear surface (9b).

2. Sole structure according to claim 1, characterized in that the plate (4) has a forefoot region (18) of U-shaped geometry whose base forms the front portion (4a) from which extend two front segments (19a, 19b) of respectively a branch (13a, 13b).

3. Sole structure according to claim 2, characterized in that the forefoot region (18) is curved by having its front edge (20) over its rear edge (21).

4. Sole structure according to any one of claims 2 or 3, characterized in that the forefoot region (18) extends longitudinally over between 20% and 30% of the total length of the plate (4).

5. Sole structure according to any one of claims 1 to 4, characterized in that the branches (13a, 13b) each have an intermediate segment (22a, 22b) extending at least partially opposite a metatarsophalangeal region (23) of the midsole (1).

6. Sole structure according to claim 5, characterized in that the intermediate segment (22a) of the long branch (13a) has a length which is greater than the length of the intermediate segment (22b) of the other branch (13b).

7. Sole structure according to any one of claims 5 or 6, characterized in that the rear edge (26) of the intermediate segment (22b) of the short branch (13b) forms the free end (16) of said short branch (13b).

8. Sole structure according to any one of claims 1 to 7, characterized in that only the long arm (13a) has a rear segment (27) which extends opposite a midfoot region (28) and at least partially opposite a heel region (12) of the midsole (1).

9. Sole structure according to any one of claims 1 to 8, characterized in that the long arm (13a) is the lateral arm.

10. Sole structure according to any one of claims 1 to 9, characterized in that the length of the short arm (13b) is 20% to 50% of the length of the long arm (13a).

11. Sole structure according to any one of claims 1 to 10, characterized in that the rear portion (4b) of the plate (4) has a maximum width which is between 40% and 60% of the maximum width of said plate.

12. Sole structure according to any one of claims 1 to 11, characterized in that the plate (4) is formed of a composite material comprising stiffening fibers, in particular carbon, glass, and / or aramid fibers.

13. Sole structure according to any one of claims 1 to 12, characterized in that the intermediate sole (1) comprises two blocks respectively upper (1a) and lower (1b) made of cellular polymer material, the stiffening plate (4) being disposed between said blocks.

14. Sole structure according to any one of claims 1 to 13, characterized in that it has a lower cavity (15) opening into the light (14) of the stiffening plate (4).

15. Footwear article comprising a sole structure according to any one of claims 1 to 14 and an upper mounted on said structure forming with it a space for receiving a user's foot.

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