Patent Application
20250024913
The present invention generally relates to athletic footwear and, more particularly, to footwear that enhances the performance of a wearer by providing increased stability, cushioning and energy return.
When running or walking a person's foot transitions through three phases of contact with each stride. Initially, runners and walkers typically strike the ground with their heel. As a result, the heel experiences significant impact loads, which are absorbed by the heel bone. Because this is a dynamic force, the impact load on the heel can be several times the walker or runner's body weight. Furthermore, the impact load is transmitted up the legs to the walker or runner's ankle, knee and hip joints.
The second phase commences when the walker or runner's body weight shifts forward. When the walker or runner's body weight shifts forward, the load in the foot shifts away from the heel towards the middle portion of the foot. In addition, the arch of the foot compresses, with the sole taking the entire weight of the body. Then the foot then rolls toward the metatarsals, which creates a torsional twisting effect due to asymmetrical nature of the foot, including the varying lengths of the toes. This may cause the foot to tilt toward to the inside (medial portion) of the foot or to the outside (lateral portion) of the foot placing additional strains on the joints and ligaments.
As the foot continues to roll forward, the walker or runner's weight is transferred to the forefoot and the metatarsal bones. This stress is distributed across the whole width of the forefoot by the muscles, ligaments, and tendons across the metatarsals.
In an attempt to reduce the impact forces on knees and ankle joints and thereby reduce the risk of injury, current shoe designs typically incorporate multiple layers of foam cushioning, which are believed to reduce impact loads. Foam cushioning material however, tends to degrade and become compacted over time and thereby loses its cushioning effect. Foam cushioning also does little to store and return energy during the gait cycle.
Consequently, there is a need to provide footwear that reduces the risk of injury to the wearer, especially to the wearer's ankle, knee and hip joints, and, ideally, returns energy so as to enhance the wearer's performance while walking or running or engaging in other athletic activities.
The present invention provides a sole for an athletic shoe, the sole comprising an upper midsole, an upper shank, a lower midsole, a lower shank and an outsole. The upper midsole, lower midsole and outsole each include a heel region and a forefoot region. In the athletic shoe of the present invention the upper shank is disposed between the upper midsole and the lower midsole and typically above a void space or channel formed in the lower midsole. The upper shank, in some embodiments, forms an upper boundary of the void space. The lower shank is disposed between the lower midsole and the outsole and below the void space. In some embodiments, the lower midsole may include multiple void spaces.
In the exemplary embodiments, the upper shank and lower shank are composed of different materials, with the lower shank generally being made of a relatively stiff material such as carbon fiber and the upper shank being made of a relatively flexible material, in comparison to upper shank, such thermoplastic polyurethane (“TPU”). The upper and lower shanks surround the void space in the lower midsole and act similar to a pair of leaf springs to both reduce impact loading at the heel during a foot strike and to return energy as the wearer's foot rolls through the gait cycle.
The upper and lower shanks being disposed above and below the lower midsole, are both stiffer then the midsole material, typically EVA, and therefore tend to oscillate with running or walking motion. That is, the upper and lower shanks move toward each other under the compression of a foot strike with the ground and tend move away from each other when the wearer's foot lifts off the ground during the gait cycle. The void space provides for greater compression and spring-back of the upper and lower shanks than would otherwise be possible if the space between the shanks solely comprised foam cushioning material.
Three principle exemplary embodiments are presented in detail, along several variations. In a first principal embodiment, a single void space, disposed approximately under a wearer's arch is provided. This embodiment provides relatively soft support under a wearer's arch and relatively firm support at the approximate center of pressure of a wearer's heel and at the approximate center of pressure of a wearer's forefoot, i.e. under the balls of a wearer's foot. This configuration is suitable for general athletic shoe use such as walking or running, for field games such as baseball and socker, as well as for numerous court games such as basketball, tennis, pickle ball and the like.
In a second principal embodiment, a single void space, disposed approximately under a wearer's heel is provided. This embodiment provides relatively soft support under a wearer's heel and relatively firm support under a wearer's arch and under the balls of a wearer's foot. This configuration is well-suited for general athletic use where it is desired to have a softer heel strike and additional arch support.
In a third principal embodiment, a single void space is disposed approximately under a wearer's arch and the lower midsole comprises a relatively thick foam cushion. This embodiment provides relatively soft support under a wearer's arch, exceptional cushioning under a wearer's heel and firm support under the balls of a wearer's foot. This embodiment is particularly well-suited for walking and running.
In a fourth principal embodiment, two void spaces are provided. The first void space is located under the approximate center of pressure of a wearer's heel and the second void space is located under approximate center of pressure of a wearer's forefoot, i.e. the balls of a wearer's foot. This embodiment provides relatively soft support under a wearer's heel and the balls of a wearer's foot and relatively firm support under a wearer's arch. This configuration is suitable for general athletic shoe use where a wearer desires relatively firm arch support.
In the exemplary embodiments of the dual-shank athletic shoe of the present invention, the foam cushioning material comprises ethylene-vinyl acetate (“EVA”) or like foam materials. In the exemplary embodiments the upper shank is fabricated from TPU or other moderately flexible plastic material. In the exemplary embodiment, the lower shank is fabricated from relatively stiff, but still flexible carbon fiber material. The outsole comprises a rubber outer layer typically having a lug pattern on its external surface optimized to grip and provide ethylene-vinyl acetate traction with the ground. A complete athletic shoe may be provided using the sole designs of the present invention by adding an upper and an insole. Uppers are typically made of fabric or leather or a combination of both. Insoles are typically from a soft foam materials. Suitable designs for shoe uppers and insoles are known in the art.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
With reference to
The first embodiment 10A of the athletic shoe sole may be divided into approximately three regions, i.e. a heel region 24, an arch region 26 and a forefoot region 28. The athletic shoe sole 10 further has an approximate heel center of pressure 54 which corresponds to the approximate center of pressure of a wearer's heel and an approximate forefoot center of pressure 56 that corresponds to the approximate center of pressure of the balls of a wearer's foot.
The upper midsole 12 has an aft end 50 and a forward end 52. The lower midsole 16 has an aft end 46 and a forward end 48 and includes a relieved area 23, which forms the void space 22, which is located in the arch region 26 of the athletic shoe sole 10. The void space 22 has a length 30 that corresponds approximately to the length of a wearer's arch and a width which corresponds approximately to the width of the lower midsole. Suitable materials for the upper midsole 12 and the lower midsole 16 include ethylene-vinyl acetate (“EVA”) or like soft foam materials.
The upper shank 14 has an aft end 36 and a forward end 38 and is disposed between the upper midsole 12 and the lower midsole 16 and forms an upper boundary 34 of the void space 22. The lower shank 18 has an aft end 40 and a forward end 42 is disposed between the lower midsole 16 and the outsole 20. In the exemplary first embodiment 10A the athletic shoe sole, the aft end 36 of the upper shank 14 is connected to the aft end 40 of the lower shank 18 to provide flexing between the shanks during a gait cycle while walking or running. The aft ends of the shanks need not be connected, however. In the exemplary first embodiment 10A of the athletic shoe sole, the forward end 38 of the upper shank 14 is not connected to the forward end 42 of the lower shank 18. The outsole 20 comprises a durable rubber outer layer typically having a lug pattern 44 on its external surface optimized to grip and provide traction with the ground.
In the exemplary first embodiment 10A of the athletic shoe sole of the present invention, it is preferred that the lower shank be stiffer than the upper shank as this configuration is believed to provide superior energy return characteristics. Achieving a particular stiffness for a shank may be accomplished through a combination of material choice and/or shank thickness. In the exemplary embodiment of the athletic shoe sole 10, the upper shank 14 and lower shank 18 are composed of different materials, with the lower shank 18 being fabricated from carbon fiber and the upper shank 14 being fabricated from thermoplastic polyurethane (“TPU”). In general, suitable materials for the upper shank 14 and lower shank 18 include thermoplastic polyurethane (“TPU”) and like plastic materials, as well as carbon fiber and metallic materials with spring properties such as a variety of steel alloys.
The upper shank 14 and the lower shank 18 surround the void space 22 in the lower midsole 16 and thereby act similar to a pair of springs to both reduce impact loading at the heel during a foot strike and to return energy as the wearer's foot rolls through the gait cycle. The upper and lower shanks 14 and 18 are both configured to be stiffer then the lower midsole 16 which is comprised of a relatively soft, shock absorbing foam material such as EVA. Therefore, the upper and lower shanks 14 and 18 tend to oscillate with running or walking motion. That is, the upper and lower shanks 14 and 18 move toward each other under the compression of a foot strike with the ground and tend move away from each other when the wearer's foot lifts off the ground during the gait cycle. In the void space 22, no damping of the oscillating motion of the upper and lower shanks 14 and 18 occurs which provides for both greater compression and spring-back of the upper and lower shanks than would otherwise be possible if the space between the shanks solely comprised foam cushioning material.
During manufacturing, the five layers which comprise the first embodiment 10A athletic shoe sole of the present invention, i.e. the upper midsole 12, upper shank 14, lower midsole 16, lower shank 18 and the outsole 20 are bonded together to form a unitary sole. Materials and methods for bonding shoe layers are known in the art.
With continued reference to
A complete athletic shoe may be provided using the first embodiment 10A of the athletic shoe sole design of the present invention by adding an upper 58 and, typically, an insole 60 (not shown). Uppers are typically made of fabric or leather or a combination of both. Insoles are typically made from soft foam materials. Suitable designs for shoe uppers and insoles are known in the art.
With reference to
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The upper midsole 12 has an aft end 50 and a forward end 52. The split-shank 62 is dual spring like structure that includes an upper shank portion 64 and a lower shank portion 66. The upper shank portion 64 has a free aft end 68 and a forward end 78. The lower shank portion 66 has a free aft end 70 and a forward end 80. The forward ends 78 and 80 of the upper and lower shank portions 64 and 66 blend or join to form a single forefoot shank portion 74 having a forward end 82. In the exemplary embodiment, the split-shank 62 is a molded component and consequently the upper shank portion 64 and lower shank portion are made from the same material. The relative stiffness of the upper and lower shank portions 64 and 66 may be varied by changing the thickness of each shank portion. The split-shank 62 allows the upper shank portion 64 to flex relative to other portions of the upper shank portion 64 during the gait cycle while walking or running. Similarly, the split-shank 62 allows the lower shank portion 66 to flex relative to other portions of the lower shank portion 66 during the gait cycle while walking or running. Although the split-shank 62 is formed as a unitary component molded of a single material, each of the upper and lower shank portions 64 and 66 could alternatively be made as separate components from separate materials and bonded together at the forefoot shank portion 74.
With continued reference to
Suitable materials for the split-shank 62 include TPU and like plastic materials, as well as carbon fiber and metallic materials with spring properties such as a variety of steel alloys. Suitable materials for the upper midsole 12 and heel pad 76 include EVA and like plastic foam materials. The outsole 20 comprises a durable rubber outer layer typically having a lug pattern 44 on its external surface optimized to grip and provide traction with the ground.
With continued reference to
During manufacturing, the components which comprise the third embodiment 10C of the athletic shoe sole of the present invention, i.e. the upper midsole 12, the split-shank 62, the heel pad 76 (disposed between the upper and lower shank portions 64 and 66) and the outsole 20 are bonded together to form a unitary sole. Materials and methods for bonding shoe layers are known in the art.
The heel pad 76 of the third embodiment 10C of the athletic shoe sole comprises a relatively thick foam cushion. Therefore, this embodiment provides exceptional cushioning and shock absorption during heel strikes which make this embodiment particularly well-suited for running and general high-impact activities.
With reference to
A further difference of the fourth embodiment 10D is that the aft end 36 of the upper shank 14 does not contact the aft end 40 of the lower shank 18. Rather the upper and lower shanks 14 and 18 remain separated from each other by the lower midsole 16. Like the first embodiment 10A, in the fourth embodiment 10D, the upper and lower shanks 14 and 18 are separated at their forward ends 38 and 42.
For reference, like the first and second embodiments 10A and 10B, the five layers of the fourth embodiment 10D are the upper midsole 12, upper shank 14, lower midsole 16, lower shank 18 and outsole 20. A heel void space 22A is disposed approximately under a wearer's heel and a forefoot void space 22B is disposed under the balls of a wearer's foot. The upper shank 14 forms an upper boundary of the heel void space 22A and the forefoot void space 22B. During manufacturing, the layers that comprise the fourth embodiment 10D of the athletic shoe sole are bonded together to form a unitary sole.
The heel and forefront void spaces 22A and 22B provide the fourth embodiment 10D of the athletic shoe sole with relatively soft support under both a wearer's heel and the balls of a wearer's foot and firmer support under a wearer's arch. This configuration is well-suited for general athletic shoe use.
With reference to
A further difference of the fifth embodiment 10E is that the aft end 36 of the upper shank 14 does not contact the aft end 40 of the lower shank 18. Rather the upper and lower shanks 14 and 18 remain separated from each other by the lower midsole 16. Like the first embodiment 10A, in the fourth embodiment 10D, the upper and lower shanks 14 and 18 are separated at their forward ends 38 and 42.
For reference, like the first embodiment 10A, the five layers of the fifth embodiment 10E are the upper midsole 12, upper shank 14, lower midsole 16, lower shank 18 and outsole 20. The single, elongated void space 22 is disposed under a wearer's heel and arch. The upper shank 14 forms an upper boundary of the elongated void space 22. During manufacturing, the layers that comprise the fifth embodiment 10E of the athletic shoe sole are bonded together to form a unitary sole.
The single, elongated void space 22 of the fifth embodiment 10E of the athletic shoe sole provides relatively soft support under both a wearer's heel and arch. This configuration is suited for general athletic shoe use. A complete athletic shoe may be provided by adding an upper 58 and typically in an insole 60 (not shown) to the fourth embodiment 10D of the athletic shoe sole of the present invention. Suitable designs for shoe uppers and insoles are known in the art.
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In each of the embodiments the athletic shoe sole of the present invention, the midsoles or midsole is fabricated from ethylene-vinyl acetate (“EVA”) foam or a like foam material. The upper shank may be fabricated from thermoplastic polyurethane (“TPU”) or other moderately flexible plastic material. The lower shank may be fabricated from a relatively stiff, but still flexible carbon fiber or like material. It should be noted that both the upper and lower shanks could be made from the same material. In the exemplary embodiments, the lower shank is typically stiffer than the upper shank. In other embodiments however, it may be preferable for the upper shank to be stiffer than the lower shank.
In each of the embodiments of the athletic shoe sole of the present invention, the outsole 20 comprises a hard rubber outer layer typically having a lug pattern 44 on its external surface optimized to grip and provide traction with the ground.
A complete athletic shoe may be provided using any of the athletic shoe sole embodiments 10A to 10N by adding an upper 58 and, typically, an insole 60 (not shown). Suitable designs for shoe uppers and insoles are known in the art.
The foregoing detailed description and appended drawings are intended as a description of the presently preferred embodiment of the invention and are not intended to represent the only forms in which the present invention may be constructed and/or utilized. Those skilled in the art will understand that modifications and alternative embodiments of the present invention which do not depart from the spirit and scope of the foregoing specification and drawings, and of the claims appended below are possible and practical. It is intended that the claims cover all such modifications and alternative embodiments.
This is a utility patent application of U.S. Patent Application No. 63/514,297, filed Jul. 18, 2023 and titled “Dual Shank Athletic Shoe,” the contents of which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63514297 | Jul 2023 | US |
