Patent Grant
8387279
The present invention relates to a shoe sole and a shoe incorporating the shoe sole and, in particular, to a shoe sole including a horizontal indentation in a peripheral sidewall of the shoe sole and preferably additional structure that can be tuned to offset a wearer's side-to-side balance and thereby encourage a wearer's conditioning and toning.
Modern athletic footwear typically include an outsole, midsole, and insole. The midsole is positioned between the ground-contacting outsole and the insole and typically includes one or more foams for attenuating impact forces generated upon the contact of a wearer's shoe on the ground. Foams such as ethelene vinyl acetate (EVA) also have resilience for energy return and are typically included in the midsole of modern athletic footwear. Athletic shoes can also include additional elements in portions of the midsole to impart a desired balance of shock-absorption (cushioning), energy return, and stability to various the user.
For example, U.S. Pat. No. 6,789,332 to Scholz discloses an L-shaped spring element attached to a top support plate. The spring element encompasses a damping element from the side and from below. The L-shaped spring, which enhances energy return, contacts the ground from below and is deflected upward, simultaneously with the damping element positioned above it, on ground contact of the sole. A downward directed restoring force is produced when the foot pushes off the ground. Overpronation or oversupination can be selectively minimized by using a less soft material for the damping material, thereby adding stability to the medial or lateral side respectively.
U.S. Pat. No. 6,216,365 to Cohen discloses a shock-absorbing unit with an effective heel member having a spine portion and elastically deformable flat spring elements branching out from the spine and rising upward to contact a top plate. A second effective member can be positioned with its spine below and contacting the first spine, with elastically deformable flat spring elements branching out and downward to contact a heel plate. A foam pad is positioned between each spine and adjacent plate. The shock-absorbing unit can be designed for specific athletic activities or for therapeutic purposes by modifying the stiffness of one or more spring elements.
U.S. Pat. No. 5,185,943 to Tong et al. discloses a resilient insert member to enhance energy return which can be positioned sandwiched between an outsole and midsole, or encapsulated in the midsole or outsole. The insert member has a central body portion and extensions which extend outwardly and downwardly from the central body portion. The extensions move outward as forces impinge on the sole, and act as a spring to return the sole to its original shape. The insert member may be “tuned” by adding apertures to those extension members located in specific areas of the sole where additional flexibility is desired and building up those extension members where it is desirable for the extension member to be more rigid or less compressible.
U.S. Pat. No. 7,421,805 to Geer discloses a support structure for a shoe that includes an elongated member that extends along the length of the shoe and a number of lateral members that extend perpendicularly from the elongated member. The lateral members may extend in an upward or downward direction or may remain in a horizontal plane.
While athletic shoes are usually designed with stability in mind, some prior art shoes are intentionally designed to promote a lengthwise instability. For example, “EasyTone” is a shoe sold by Reebok International, Ltd. that is intended to create a natural instability and a feeling akin to walking on a sandy beach. This is achieved by inserting balance pods under the heel and forefoot of the shoes. Air travels between the forefoot and heel pod to create soft cushioning. The moving air creates a natural instability and forces your muscles to adapt to the air volume within the pods. The instability encourages toning in the hamstrings, gluteus maximus, and calves.
Another known shoe designed to promote instability is the “MBT” model sold by Masai USA Corp. This shoe uses a PU midsole which has a “balancing area” in the metatarsus region, causing a rocking motion forward and rearward of the balancing area, even when standing. Also included is a soft heel pad that is intended to mimic beach sand. This design is intended to stimulate muscle toning and to burn extra calories in that the muscles tense in reaction to the natural instability. A similar design is described in U.S. Pat. No. 6,421,935 to Bartlett.
U.S. Pat. No. 291,490 to Buch shows leaf springs mounted between an outsole and a midsole.
None of these prior art references provides a shoe sole and a shoe incorporating the shoe sole, which includes a horizontal indentation in a peripheral sidewall of the shoe sole and preferably additional structure that can be tuned to offset a wearer's side-to-side balance and thereby encourage a wearer's conditioning and toning.
The present invention relates to a shoe sole and a shoe incorporating the shoe sole that can be tuned to offset a wearer's side-to-side balance and thereby encourage a wearer's conditioning and toning. The present inventions further relates to a shoe sole and a shoe with additional structures that can be used to additionally affect a wearer's balance and to tune stability, energy return and cushioning.
The present invention relates to a shoe sole which includes a midsole including an upper surface that has a width that underlies and supports a wearer's foot. The midsole also includes an upper midsole portion and a lower midsole portion adjacent and below the upper midsole portion in at least a heel portion, and a lower surface. A peripheral sidewall of the midsole extends between the upper surface and the lower surface. The upper midsole portion is undercut at least at its heel portion to define a horizontal indentation. The horizontal indentation has a depth in the peripheral sidewall along the medial and lateral sides of the midsole and a rear of the heel portion of the midsole. A balancing portion extends between the horizontal indentation on the medial and lateral sides of the indentation. The peripheral sidewall includes an upper peripheral sidewall angled upward from the horizontal indentation toward the upper surface and a lower peripheral sidewall angled downward from the horizontal indentation toward the lower surface to form a peripheral gap that widens in a direction away from a center of the shoe sole. The balancing portion has a width less than the width of the upper surface of the midsole. The midsole is adapted to upset a wearer's balance transversely to a longitudinal axis of the shoe sole, thereby forcing a wearer of the article of footwear to adjust one's walking gait to maintain a center of pressure over the balancing portion.
The upper and lower midsole portions can be separate upper and lower midsole layers or can be formed as one unitary piece.
In one aspect, the shoe sole can also include a structure disposed on the peripheral sidewall along at least one of the medial and lateral side of the shoe sole. The structure includes a base portion positioned along the horizontal indentation and a first plurality of upper extensions. The upper extensions are preferably spaced apart along the upper peripheral sidewall and extend outwardly from the base portion toward the upper surface.
The structure can additionally, or alternatively, include a second plurality of lower extensions. The lower extensions are preferably spaced apart along the lower peripheral portion and extend outwardly from the base portion toward the lower surface. The first plurality of upper extensions is preferably staggered with the second plurality of lower extensions such that the upper extensions are arranged in an alternating pattern with the lower extensions along the base portion.
Any variation of this structure with upper and/or lower extensions can be positioned along either a medial or lateral side of a shoe sole, or as a U-shaped structure, around the rearmost part of a heel portion and along both medial and lateral sides of a shoe sole. These structures can be external, in that except for an optional anchoring tab that can extend inward from the structure between an upper and lower midsole layer, they are adapted to be mounted to the peripheral sidewall. In one aspect, any of the structures having upper and/or lower extensions without a central portion can be mounted to the peripheral sidewall of an upper and lower midsole portion formed as one unitary piece.
The depth of the horizontal indentation can vary along the length of the shoe sole and from side to side, and can also extend into the midfoot and into one or both sides of a forefoot. In one preferred example of a shoe sole formed in accordance with the present invention, the depth of the horizontal indentation is deeper on the medial side than on the lateral side in the forefoot and is deeper on the lateral side than on the medial side in the heel portion.
The present invention also relates to a shoe sole which includes any of the midsoles of the present invention in combination with an outsole. In one aspect, the outsole preferably has a lower surface that includes a raised portion having a width less than the width of the upper surface of the midsole. The raised portion is adapted to promote instability in a wearer's walking gait. The raised portion protrudes generally from the center of the outsole at least in the heel portion. Preferably, a height of the raised portion increases in a direction from a forefoot portion of the shoe sole toward the rear of the heel portion of the shoe sole. A width of the raised portion in another aspect is less than two-thirds the width of the outsole.
In a different aspect, at least a portion of an outsole of the shoe sole of the present invention extends from the forefoot to the heel portion of the shoe sole and has a lower surface that includes curvature about an axis of the shoe sole that runs from the forefoot portion to the heel portion of the shoe sole. The curvature results in the outsole having a downward protruding portion for engaging the ground prior to adjacent portions of the outsole.
The present invention additionally relates to a shoe sole for an article of footwear that includes a midsole. The midsole includes an upper surface that has a width that underlies and supports a wearer's foot. The midsole also includes an upper midsole layer and a lower midsole layer disposed below the upper midsole layer in at least a heel portion, and a lower surface. The midsole has a peripheral sidewall between the upper surface and the lower surface. The upper midsole layer of at least the heel portion is undercut at its periphery to define a horizontal indentation having a depth in the peripheral sidewall of the midsole along the medial and lateral sides and a balancing portion therebetween. The peripheral sidewall includes an upper peripheral sidewall angled upward from the horizontal indentation toward the upper surface and a lower peripheral sidewall angled downward from the horizontal indentation toward the lower surface to form a peripheral gap that widens in a direction away from a center of the shoe sole. The balancing portion has a width less than the width of the upper midsole layer. The midsole is preferably adapted to upset a wearer's balance transversely to a longitudinal axis of the shoe sole, thereby forcing a wearer of the article of footwear to adjust one's walking gait to maintain a center of pressure over the balancing portion.
This shoe sole also includes a structure disposed on the peripheral sidewall along the medial and lateral side of the shoe sole. The structure includes a base portion positioned along the horizontal indentation and a first plurality of lower extensions. The lower extensions are preferably spaced apart along the lower peripheral portion on each of the medial and lateral sides, and extend outwardly from the base portion and toward the lower surface. The structure also preferably includes a second plurality of upper extensions. The upper extensions are spaced apart along the upper peripheral sidewall on each of the medial and lateral sides and extend outwardly from the base portion and toward the upper surface. The structure also includes a central portion disposed between the upper midsole layer and the lower midsole layer which includes a plurality of concavely curved leaf springs formed substantially transverse to a longitudinal axis of the shoe sole. Each concavely curved leaf spring is formed in one continuous upward arc from and with a laterally and medially positioned lower extension. The central portion also preferably includes a plurality of convexly curved leaf springs formed substantially transverse to a longitudinal axis of the shoe sole. Each convexly curved leaf spring is formed in a continuous downward arc from and with a laterally and medially positioned upper extension. The second plurality of upper extensions is preferably staggered with the first plurality of lower extensions such that the upper extensions are arranged in an alternating pattern with the lower extensions along the base portion and the integrally formed plurality of concavely curved leaf springs is staggered with the plurality of convexly curved leaf springs such that the concavely curved leaf springs are arranged in an alternating pattern with the convexly curved leaf springs. The height of the concavely curved leaf springs can be greater than the height of the convexly curved leaf springs.
In other aspects, this shoe sole can additionally include any of the outsoles of the present invention.
The present invention further relates to a shoe sole for an article of footwear that includes a midsole having an upper surface that has a width that underlies and supports a wearer's foot, a lower surface, and a structure also disposed between the upper and lower midsole layer. The structure includes a base portion and a central portion. The base portion has a medial portion on a medial side of the shoe sole and a lateral portion on a lateral side of the shoe sole. The central portion, which is disposed between the medial and lateral base portions, includes a plurality of concavely curved leaf springs. Each of the concavely curved leaf springs is formed in a continuous upward arc toward a center of the shoe sole from transversely opposed portions of the base portion located on the lateral and medial sides of the shoe sole. The central portion also includes a plurality of convexly curved leaf springs. Each of the convexly curved leaf springs is formed in a continuous downward arc from transversely opposed portions of the base portion located on the lateral and medial sides of the shoe sole.
In one aspect, the concavely curved leaf springs are arranged in an alternating pattern with the convexly curved leaf springs. In another aspect, the midsole also includes an upper midsole layer and a lower midsole layer. The upper midsole layer includes recesses in its lower surface for receiving the concavely curved leaf springs and the lower midsole layer includes recesses in its upper surface for receiving the convexly curved leaf springs. In this way, the lower midsole layer can form a gasket to fill the spaces between the lower midsole surface and the leaf springs.
The present invention still further relates to a shoe sole for an article of footwear that includes a midsole having an upper surface that has a width that underlies and supports a wearer's foot. The midsole also includes an upper midsole layer and a lower midsole layer disposed below the upper midsole layer in at least a heel portion, and a lower surface. A peripheral sidewall extends between the upper surface and the lower surface. The upper midsole layer of at least the heel portion is undercut at its periphery to define a horizontal indentation having a depth in the peripheral sidewall of the midsole along the medial and lateral side and a balancing portion therebetween. The peripheral sidewall includes an upper peripheral sidewall angled upward from the horizontal indentation toward the upper surface and a lower peripheral sidewall angled downward from the horizontal indentation toward the lower surface to form a peripheral gap that widens in a direction away from a center of the shoe sole. The balancing portion has a width less than the width of the upper midsole layer. The midsole is preferably adapted to upset a wearer's balance transversely to a longitudinal axis of the shoe sole, thereby forcing a wearer of the article of footwear to adjust one's walking gait to maintain a center of pressure over the balancing portion.
This shoe sole also preferably includes a structure disposed on the peripheral sidewall along the medial and lateral side of the shoe sole. The structure includes a base portion positioned along the horizontal indentation and a first plurality of lower extensions. The lower extensions are preferably spaced apart along the lower peripheral portion on each of the medial and lateral side. The lower extensions extend outwardly from the base portion and toward the lower surface. The structure also preferably includes a central portion disposed between the upper midsole layer and the lower midsole layer. The central portion includes a plurality of concavely curved leaf springs. Each of the concavely curved leaf springs is preferably formed in a continuous arc upward from one of the lower extensions on the lateral side and one of the lower extensions on the medial side.
In another aspect, the shoe sole can also include a second plurality of upper extensions extending outwardly along said peripheral sidewall toward the upper surface, and a plurality of convexly curved leaf springs formed in a continuous arc downward from the upper extensions located on the medial and lateral side. In a preferred embodiment, a height of at least one of the concavely curved leaf springs is greater than a height of at least one of the convexly curved leaf springs.
Additional features of the shoe sole element of the present invention will be evident from the drawings and description provided below. Although these illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be applied therein by one skilled in the art without departing from the scope or spirit of the invention.
A shoe sole of the present invention has a medial side or portion, a lateral side or portion, and a forefoot, midfoot, and heel or rearfoot portion as those terms are commonly known.
The present invention, which provides a shoe sole for an article of footwear and an article of footwear which includes a deep horizontal indentation in a peripheral sidewall of at least a heel portion of the shoe sole and preferably additional structure that can be tuned to encourage a wearer's conditioning and toning, can be better understood from the following description of preferred embodiments, taken in conjunction with the accompanying drawings. It should be apparent to those skilled in the art that the described embodiments of the present invention provided herein are merely exemplary and illustrative and not limiting. All features disclosed in the description may be replaced by alternative features serving the same or similar purpose, unless expressly stated otherwise. Therefore, numerous other embodiments of the modifications thereof are contemplated as falling within the scope of the present invention and equivalents thereto.
The present invention relates to a shoe sole that can be selectively tuned to provide a desired amount of cushioning, energy return, and stability or instability to targeted portions of a shoe sole. The shoe soles of the present invention can be tuned to upset the side-to-side or transverse balance of a person wearing an article of footwear incorporating the shoe sole. By upsetting the wearer's balance, the shoe soles of the present invention preferably cause the wearer to work harder to maintain one's balance, in a manner akin to balancing on a balance beam or board—by adjusting one's posture to maintain one's center of weight over a central balancing portion of the shoe sole. The shoe soles thereby promote the wearer's conditioning and toning. Preferably, the shoe soles of the present invention can cause an increase in muscle activation in wearers and an increase in calorie burning compared to conventional shoe soles. Targeted muscle groups include the calf, quad, gluteus maximus and hamstring muscle groups.
In a shoe sole of the present invention, as shown in the embodiment of
Referring also to
In order to advantageously induce a side-to-side imbalance in a wearer of a shoe having the shoe sole 10, the upper midsole portion 16 is undercut at its periphery to create a deep horizontal indentation 28 in the peripheral sidewall 26 along at least the medial and lateral sides of the shoe sole 10 in at least the heel portion, and preferably continuously around the rear of the heel portion as well. As a result, the peripheral sidewall 26 is angled upward and outward from the horizontal indentation 28 toward the upper surface 20 of the upper midsole portion 16 to form an upper peripheral sidewall 30. A corresponding wedge-shaped gap is chiseled out of the top of the lower midsole portion 18 to form a lower peripheral sidewall 32 angled outward and downward from the horizontal indentation 28 toward the lower surface 24. A peripheral gap 34 is thus formed between the upper peripheral sidewall 30 and lower peripheral sidewall 32 that widens in a direction away from the center of the shoe sole 10.
The horizontal indentation 28 has a depth measured horizontally inward from the outer edge of the upper midsole portion 16. A narrowed balancing portion 38 in at least the heel portion of the midsole 14 is therefore formed in the region between the medial and lateral horizontal indentations 28, which defines an area over which a wearer of the shoe sole must place one's weight in order to stay balanced. By making the transverse width 40 of the balancing portion 38 less than the width 22 of the midsole 14 that underlies the wearer's foot, the wearer's side-to-side balance is upset, which forces the wearer to have to work to adjust one's gait and shift one's weight to maintain a center of pressure over the balancing portion 38. By also undercutting the midsole to extend the horizontal indentation 28 around the rear of the heel, an additional longitudinal imbalance is imparted and creates the feel of one's heel pushing into a sandy surface on heel strike.
Various properties of the shoe sole of the present invention can be tuned to increase or decrease the degree and/or direction of instability imparted to a wearer of an article of footwear incorporating the shoe sole. Tunable properties of embodiments of the shoe sole of the present invention include the thickness and the material of the upper midsole portion and lower midsole portion, which can also be varied throughout the different regions or portions of the shoe sole (forefoot, midfoot, heel, medial, lateral portions).
For example, the lower midsole portion is preferably made of ethelene vinyl acetate (EVA) foam, polyurethane (PU) foam or foam blends or any other suitable materials can be used as well. Its density and other properties can be varied to change the amount of cushioning and shock absorption that it provides. The upper midsole portion is also preferably made of ethelene vinyl acetate (EVA) foam, polyurethane (PU) foam or foam blends or any other suitable materials can be used as well. Its density and other properties can be varied to change the amount of cushioning and shock absorption that it provides. In one embodiment, the upper and lower midsole portions are separate upper and lower midsole layers that can be formed of materials of differing densities and/or materials.
For example, the upper midsole portion 16 of
The upper and/or lower midsole portion in various embodiments can also be thicker in the rearfoot portion in order to provide more cushioning in that region, and/or to provide heel lift.
In another embodiment, the upper midsole portion 16 and lower midsole portion 18 are formed as a single unitary piece over the length of the shoe sole 10.
In yet another embodiment of the shoe sole 10, the upper 16 and lower 18 midsole portions in at least the heel are formed from different midsole layers, and the lower midsole portion extends only over a heel, or optionally also over at least a midfoot portion of the shoe sole, but not into the forefoot. In contrast, the upper midsole portion extends from the heel portion into the midfoot and forefoot portions, where the entire thickness of the midsole in the forefoot portion is integrally formed from the same material as the upper midsole portion in the heel.
Referring still to
The centering of the balancing portion 38 can also be tuned by making the depth 36 of the horizontal indentation 28 deeper in some portions of a shoe sole 15 than in other portions. In this way, a “balancing path” 222, as can be seen in
As shown in
The horizontal indentation 28 can also be extended into the midfoot along either the medial or lateral side of a shoe sole, or both, to extend the path length over which a wearer must exert extra effort to maintain balance. As shown in
Referring again to
In a further embodiment, the depth 36 of the horizontal indentation 28 is at least 10% of the width 22 of the portion of the upper midsole portion 16 underlying the wearer's foot along a substantial portion of the heel portion of the shoe sole 10. In another embodiment, the depth 36 of the horizontal indentation 28 is at least 14% of the width 22 of the upper midsole portion 16 underlying the wearer's foot along a substantial portion of the heel portion of the shoe sole 10.
In yet another embodiment, the depth 36 of the horizontal indentation 28 in the heel portion is between about 10% and 20%, preferably between about 14% and 20%, of the width 22.
In still another embodiment, the depth 36 of the horizontal indentation 28 in the heel portion is between about 20% and 30% of the width 22.
In a further embodiment, the depth 36 of the horizontal indentation 28 in the heel portion is between about 30% and 40% of the width 22, and can be as much as 45%.
In embodiments including a horizontal indentation 28 that extends into the midfoot and optionally into the forefoot, the depth 36 preferably tapers continuously either from the rearmost part of the heel into the forefoot, or continuously beginning forward of the heel portion into the forefoot.
In one embodiment, a depth 36 of the horizontal indentation 28 decreases to on the order of 1% in a central portion of the forefoot portion. In other embodiments, the depth 36 of the horizontal indentation 28 decreases in a central portion of the forefoot portion by about 10% of the maximum depth in the heel portion.
The angle of the undercut and thus the height of the peripheral gap 34 at the outer perimeter of the midsole can also be tuned to affect the amount of energy that the wearer must exert while walking. By making the peripheral gap 34 larger, the shoe sole 10 will compress more easily when a wearer's weight is placed over it. In one embodiment, the height of the peripheral gap 34 at the outer perimeter of the midsole 14 in the heel portion increases to at least 35% of the thickness of the midsole 14, preferably to at least 45%. In other embodiments in which the horizontal indentation 28 extends into the midfoot and optionally the forefoot, the height of the peripheral gap 34 in the midfoot portion increases to at least 20%, preferably to at least 30% of the thickness of the midsole 14, and the height of the peripheral gap 34 in the forefoot portion increases to at least 14%, preferably to at least 24% of the thickness of the midsole 14.
Embodiments of the shoe soles of the present invention described herein can include a full length outsole layer 12, which can extend under the entire midsole or any portion thereof, or may have at least a portion that extends over the full length of the shoe sole 10. In other embodiments, selectively positioned pads or pods can be disposed below portions of the midsole 14 for contacting a ground surface. In other embodiments, the lower surface of the midsole 24 forms at least a portion of the ground-contacting surface of the shoe sole 10. The outsole 12 portions or layers can be formed of any appropriate material for contacting a walking surface.
For any of the embodiments of the shoe sole described above, a structure can be disposed along a portion, or all, of the horizontal indentation in order to provide further tenability of a hoe sole formed in accordance with the present invention.
A side view of an embodiment of a shoe sole 10, for example, that incorporates a tunable structure 50 is shown in
The structure 50 includes a base portion 52 positioned along the horizontal indentation 54 and a first plurality of upper extensions 56. The upper extensions 56 are spaced out along the upper peripheral sidewall 58 and extend outwardly and upwardly from the base portion 52 toward the upper surface 60 of the upper midsole portion 62. In one embodiment, the upper peripheral sidewall 58 may have indentations formed in it to accept the upper extensions 56, so that the extensions are substantially flush with the surface of the sidewall 58. In a further embodiment of the structure 50 disposed along the horizontal indentation 54, as shown in
The tunable properties of the upper extensions 56 and lower extensions 64 include their stiffness, size, spacing and placement. The upper 56 and lower 64 extensions can be made stiffer in one region or along the entirety of the structure in order to provide more stability and more rebound capability, respectively, in that area. Alternatively, the upper 56 and lower 64 extensions can be made less stiff to provide less stability and rebound respectively in an area. The size of the upper extensions 56 and lower extensions 64 can also be tuned. For example,
In one embodiment, the length of the structure 50, 74 is restricted to the heel portion as shown in
In one embodiment of a structure 98 disposed in a horizontal indentation 100, as shown in
Referring to
As shown in
Though the base portion is preferably provided in order to form one structure 124 that can be easily mounted in a shoe sole, it is also within the scope of the invention to provide continuously arced leaf springs through the midsole that are not interconnected through a base portion.
In a preferred embodiment, the height of the concavely curved leaf springs 144 is greater than the height of convexly curved leaf springs 150.
In additional embodiments, the structure 132 further includes upper extensions 148 on the medial and lateral upper peripheral sidewalls 151 and/or lower extensions 138 on the medial and lateral lower peripheral sidewalls 142.
Each concavely curved leaf spring 144 is preferably formed continuously with one lower extension 138 on the lateral lower peripheral sidewall 142 and one lower extension 138 on the medial lower peripheral sidewall 142. Each convexly curved leaf spring 150 is preferably formed continuously with one upper extension 148 on the lateral upper peripheral sidewall 151 and one upper extension 148 on the medial upper peripheral sidewall 151.
As can be seen in
In one embodiment, the entire structure 124 can be formed of any one suitable material such as thermoplastic polyurethane (TPU) and can be integrally molded. In other embodiments, any one or more elements or type of elements (concave leaf springs 144, convex leaf springs 150, upward extensions 148, downward extensions 138), for example, in a particular location of the shoe sole 10 can be formed of a material independently selected from the following exemplary materials bearing in mind that other suitable materials are also contemplated: thermoplastic polyurethane (TPU), polyester-TPU, polyether-TPU, polyester-polyether TPU, polyvinylchloride, polyester, thermoplastic ethyl vinyl acetate, styrene butadiene styrene, polyether block amide available under the trademark Pebax®, engineered polyester available under the trademark Hytrel®, TPU blends including natural and synthetic rubbers, and blends or combinations thereof. The hardness of the material suitable for the elements of the structure can range from as low as about 25 Shore A to about 70 Shore D, depending on the desired result. The performance properties of the midsole 14 can be adjusted by changing the hardness of the structure 124. For example, it is contemplated using a more compliant material for the lateral side of the structure 124 and another stiffer material for the medial side. It is also contemplated to use a softer material for the concave springs 144 and upper extensions 148 than for the convex springs 150 and lower extensions 138. However, any combination of stiffness of the various elements and midsole layers of the shoe sole 10 is within the scope of the invention.
In any of the embodiments of a structure including a central portion, either or both of the surfaces of the upper and lower midsole layers adjacent the leaf springs can be formed with recesses shaped to accommodate the curvatures of the leaf springs. In this way, the lower midsole layer 132, for example, can form a gasket between an outsole 12 or between a lower surface of a midsole 14 and the leaf springs of central portion 128, preventing any grit or moisture from penetrating through the structure 124. The use of these recessed surfaces in the midsole layers allows continuously curved leaf springs, concave and/or convex, to be easily assembled into the midsole of a shoe sole of the present invention, as well as to be protected from too much exposure to the dirt and moisture of the environment. This construction also allows differing thicknesses of the different midsole layers, as they are aligned with the curved springs, to be placed longitudinally through the shoe sole. Therefore, both the curvature of the springs and the thicknesses of the two midsole layers can vary over the length of the shoe sole (see
Like the upper and lower midsole portions and upper and lower extensions, the properties of the convexly curved leaf springs 150 and the concavely 144 curved leaf springs in different areas, such as size, thickness, stiffness, spacing and curvature, can be varied in order to finely tune the cushioning, energy return, and stabilization properties of the shoe sole 10. The concavely curved leaf springs 144 can be made softer, for example, to increase cushioning, or harder to increase energy return. Likewise, the convexly curved leaf springs 150 can be made softer to promote instability around the foot's natural walking strike path, or harder to increase stability. In one embodiment, it is desirable to increase the softness of the convexly curved leaf springs 150 to promote a small amount of instability. A more unstable shoe sole causes a wearer to have to work harder to maintain normal pressure in the center of their strike path. Instability in the shoe sole can therefore be used to promote fitness and toning in the wearer's lower extremities. Likewise, in such a shoe sole it may be desirable to increase the softness of the concavely curved leaf springs 144, particularly in the heel, to provide a feeling akin to walking on a sandy beach. The degree of softness of the various concavely curved leaf springs 144 and convexly curved leaf springs 150 can be varied depending on the desired effect. Alternatively, proper tuning of both the convexly curved 150 and concavely curved 144 leaf springs can be used to promote stability at various areas of the shoe sole 10 for particular athletic activities.
Because of the discrete nature of the concavely curved leaf springs 144 and convexly curved leaf springs 150, different areas of the shoe sole 10, for example (forefoot, rearfoot, midfoot), on different sides (medial and lateral) of the shoe sole 10 can be independently stiffened or softened to create any desired balance of cushioning, energy return, and stability.
Additionally, the length of the structure may be tuned to direct support from the leaf springs to various areas of the shoe sole. For example,
In another embodiment of the present invention, as shown in
To induce further instability, any of the embodiments of a shoe sole including a midsole of the present invention can also include an outsole with a lower surface as described in reference to
The positioning of the raised portion 206 relative to the longitudinal center of the shoe sole may also be varied from the forefoot area of the outsole 204 to the rearfoot area of the outsole 204, by tuning the positioning of the raised portion 206 relative to the longitudinal center of the outsole 204, the balancing portion 38 of the shoe sole 10 can be changed to target different muscle groups for activation while walking.
In another embodiment, as shown in
An embodiment of an outsole 208 with a curvature about a longitudinal axis 210 can be seen in
Additionally, as shown in
As can be seen from the description above, the shoe sole of the present invention provides various means through which it can be tuned to require a wearer to have to exert additional effort in order to maintain one's balance, thereby promoting the wearer's conditioning and toning.
Any of the embodiments of a shoe sole, or of the embodiments of a structure and a shoe sole incorporating such structure, can be incorporated into a sandal, or into a shoe having an upper, or into any other article of footwear. Accordingly, an article of footwear incorporating any of the embodiments described herein is also within the scope of the invention. Such articles of footwear can be used, for example, as a walking shoe, a leisure or casual shoe, or a training shoe.
Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be applied therein by one skilled in the art without departing from the scope or spirit of the invention.
This application claims priority to U.S. Provisional Application Ser. No. 61/210,871, filed Mar. 23, 2009, the entirety of which is incorporated herein by reference thereto.
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