Stock material or miscellaneous articles – Structurally defined web or sheet – Including grain – strips – or filamentary elements in...
Reexamination Certificate
2000-01-07
2001-05-15
Sewell, Paul T. (Department: 3728)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including grain, strips, or filamentary elements in...
C428S140000, C428S107000, C428S109000, C428S110000, C428S114000, C428S113000, C404S134000, C404S070000
Reexamination Certificate
active
06231946
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a resilient, flexible structural reinforcement which may be used in or as a replacement for a resilient cushioning material, such as a shoe midsole, to provide a spring for storing and releasing energy in a manner beneficial to the user. The invention also relates to structurally reinforced shoe soles, midsoles, and to shoes incorporating such soles.
BACKGROUND OF THE INVENTION
Shoe soles, e.g., athletic shoe soles, must be flexible and typically include a patterned, ground engaging, tread layer or outsole, a midsole consisting of highly resilient porous material, and an innersole. The midsole of athletic shoes is typically formed of a softly elastic material such as foamed polyurethane or an ethylene-vinyl acetate copolymer. A softly elastic material is provided to absorb impact associated with movement of the user's foot such as walking, running, jumping, etc., and to provide a cushioning effect to the user's foot.
Although shoe midsoles must be flexible, they must nonetheless be stable to prevent a less than ideal foot strike which often results in over-supination or over-pronation of the user's stride. Over-supination or over-pronation occurs when the user's foot strikes the ground at an angle relative to the horizontal axis. Stated differently, the inside or outside of the user's foot bears the impact as the foot strikes the ground as opposed to the impact being uniformly distributed across the user's foot. This, in turn, may result in injuries to the user's joints.
It is desirable for shoe soles to relieve stresses that are imposed on a human foot during activities such as athletic activities by providing a spring arrangement. The spring arrangement stores and releases energy caused by compression of the midsole when portions of the foot (i.e., the heel and ball of the foot) impact upon the ground. The stored energy, which compresses the midsole, may be returned to the user's benefit while also assisting to avoid overuse injuries caused by repetitive impact to the body joints as the foot strikes the ground. A problem associated with shoe midsoles is wear due to creep. Creep is caused by strain experienced by the sole, e.g. the midsole, when subjected to repetitive, applied stress and results in a permanent deformation and loss of resiliency in the midsole. Creep may be particularly imminent with a less than ideal foot strike, e.g., supination or pronation of the foot. As a result, the midsole may no longer be flat when only a portion of the midsole experiences creep due to uneven repetitive stress. In turn, the useful life of the midsole is diminished thereby decreasing the life of the shoe.
SUMMARY OF THE INVENTION
In accordance with preferred embodiments of the present invention, a flexible structural reinforcement is provided for storing and releasing energy and providing stability and structured resiliency characteristics to the member it is reinforcing. Preferably, the structural reinforcement is placed within or as part of a midsole or as the midsole to provide a lightweight reinforcement for reinforcing a shoe sole to maximize its useful life. For the sake of illustration, use of the structural reinforcement within a shoe midsole will be described, but it is to be apparent that the structural reinforcement described herein has many applications in addition for a use in a shoe midsole. For example, the gridwork may serve as the midsole of the shoe sole. Thus, an outsole and an innersole may be positioned on opposing sides of the gridwork, thereby eliminating the need and expense of the softly elastic material. The structural reinforcement preferably also provides a midsole that returns stored energy resulting from foot impact upon the ground to the user's benefit by providing spring-like characteristics to the sole. A sole possessing spring-like capabilities to propel or encourage the natural foot strike of the user to lengthen the user's stride, increase the stride speed, and stabilize the user's foot and prevent permanent compression of the midsole as a result of creep is also provided by preferred embodiments of the present invention.
According to one embodiment, the invention provides a gridwork comprising sets of warp strands and sets of weft strands which has been substantially impregnated throughout with a thermosettable-B stage or fully cured resin for reinforcing resilient, compressible foam material such as is used in the midsole of shoes, e.g., athletic shoes. Shoe properties such as stored energy return, foot stability, sole expansion and/or wear may be enhanced by employing such a gridwork used in combination with compressible foam material employed in shoe midsoles, especially athletic shoes. This is achieved according to embodiments of the present invention by providing a resilient polymer cushioning material that either encapsulates or is positioned adjacent to a structural reinforcement provided in the midsole that imparts spring-like characteristics to the polymer material. In addition to enhancing various performance characteristics, the structural reinforcement provided in the midsole imparts structural integrity to the midsole contributing to its wear resistance. In preferred embodiments of the present invention, the structural member also stabilizes elongation properties of the midsole to decrease or prevent over-supination and over-pronation, particularly when used as an athletic shoe midsole.
The gridwork comprises a set of warp strands and a set of weft strands disposed at substantially right angles to each other, with each of the strands comprising at least one continuous filament, and with at least some of the strands of each set being spaced apart so as to define an open structure, and with the gridwork being impregnated substantially throughout with a thermosettable B-stage or fully cured resin. According to one embodiment, the gridwork is positioned within or as part of a compressible midsole. Alternatively, the gridwork may form the midsole of the shoe sole without the need for compressible material. One aspect of the present invention provides for a generally flat gridwork. In another embodiment, the set of warp strands of the gridwork is corrugated, e.g., into a sinusoidal configuration, having alternating high and low portions, and wherein the set of weft strands is substantially linear, so that the gridwork has a three-dimensional configuration when formed within the midsole, as part of the midsole, or as the midsole. In yet another embodiment of the present invention, the gridwork has a double corrugated shape consisting of a juxtapositioned pair of corrugated gridwork elements fixedly connected to one another in a face-to-face relationship and the gridwork is positioned within the midsole, as part of the midsole, or as the midsole. According to any one of the aforementioned embodiments, the structural reinforcement is impregnated substantially throughout with a thermosettable B-stage or fully cured resin as described previously so as to interlock the strands at their crossover points and to retain the gridwork in a semi-rigid configuration.
Alternatively, the structural reinforcement may be formed from a grid material. The grid material may be formed of a composite fabric, impregnated with a thermoset resin, and formed to include apertures. The grid material may then be corrugated according to one embodiment and mated with another corrugated grid material to form a double corrugated reinforcement. For the sake of discussion, use of the term “gridwork” encompasses woven and non-woven materials such as a grid material.
According to one preferred embodiment, the gridwork, be it flat, corrugated or double corrugated, may be positioned within the resilient midsole by an injection molding operation which also typically forms the midsole or a relatively resilient composite sheet from which midsoles can be formed. Alternatively, the gridwork may be joined with pre-formed resilient material. With respect to one embodi
Brown Bentley A.
Brown Jr. Gordon L.
Milliman Jeffery E.
Alston & Bird LLP
Arnold Troy
Sewell Paul T.
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