Patent Application
20070033833
This invention relates generally to midsoles for articles of footwear and, in particular, to midsoles for articles of footwear having multiple layers.
A conventional article of athletic footwear includes two primary elements, an upper and a sole assembly or sole structure. The upper provides a covering for the foot that securely receives and positions the foot with respect to the sole structure. In addition, the upper may have a configuration that protects the foot and provides ventilation, thereby cooling the foot and removing perspiration. The sole structure is secured to a lower portion of the upper and is generally positioned between the foot and the ground. In addition to attenuating ground reaction forces (i.e., imparting cushioning), the sole structure may provide traction and control foot motions, such as pronation. Accordingly, the upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a variety of ambulatory activities, such as walking and running.
The sole structure of athletic footwear generally exhibits a layered configuration that includes a comfort-enhancing insole, a resilient midsole formed from a polymer foam material, and a ground-contacting outsole that provides both abrasion-resistance and traction. The midsole is the primary sole structure element that imparts cushioning and controls foot motions. It is desirable to provide superior cushioning with the midsole, as well as providing a long-lasting, wear-resisant and water resistant midsole.
It is an object of the present invention to provide an article of footwear that reduces or overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.
The principles of the invention may be used to advantage to provide an article of footwear having lighter weight and improved durability. In accordance with a first aspect, an upper for an article of footwear includes an upper and a sole assembly secured to the upper. The sole assembly includes an upper layer formed of a first material and a lower layer positioned beneath the upper layer and formed of a second material. At least one finger extends downwardly from at least a portion of a periphery of the upper layer.
In accordance with another aspect, an article of footwear includes an upper and a midsole secured to the upper. The midsole includes an upper layer formed of a first material and a plurality of fingers extending downwardly about a periphery of a forefoot portion of the upper layer. A lower layer is positioned beneath the upper layer and is formed of a second material. The lower layer has at least one recess, with at least one finger being received in the at least one recess. An outsole is secured to the midsole.
In accordance with a further aspect, an article of footwear includes an upper and a sole assembly secured to the upper. The sole assembly has a midsole including a first portion formed of a first material having a first property and having a plurality of fingers extending downwardly about a least a portion of a periphery of a bottom surface thereof. A second portion is positioned beneath the first portion, and is formed of a second material having a second property different than the first property of the first portion. The second portion has a raised central portion, with the fingers extending downwardly about the raised central portion.
Substantial advantage is achieved by providing an article of footwear with a midsole having multiple layers. In particular, certain preferred embodiments of the present invention can provide footwear with improved wear-resistance while at the same time reducing the weight of the footwear.
These and additional features and advantages of the invention disclosed here will be further understood from the following detailed disclosure of certain preferred embodiments.
The figures referred to above are not drawn necessarily to scale and should be understood to provide a representation of the invention, illustrative of the principles involved. Some features of the article of footwear depicted in the drawings have been enlarged or distorted relative to others to facilitate explanation and understanding. The same reference numbers are used in the drawings for similar or identical components and features shown in various alternative embodiments. Articles of footwear as disclosed herein would have configurations and components determined, in part, by the intended application and environment in which they are used.
The present invention may be embodied in various forms. A preferred embodiment of an article of footwear 10 is shown in
Unless otherwise stated, or otherwise clear from the context below, directional terms used herein, such as rearwardly, forwardly, beneath, rear, front, inwardly, downwardly, upwardly, etc., refer to directions relative to footwear 10 itself. Footwear 10 is shown in
Sole assembly 14, which is generally disposed between the foot of the wearer and the ground, provides attenuation of ground reaction forces (i.e., imparting cushioning), traction, and may control foot motions, such as pronation. As with conventional articles of footwear, sole assembly 14 may include an insole (not shown) located within upper 12, a midsole 22, and an outsole 24. Midsole 22 is positioned beneath upper 12 and functions as the primary shock-attenuating and energy-absorbing component of footwear 10. Midsole 22 may be secured to upper 12 by adhesive or other suitable means.
Outsole 24 is positioned beneath midsole 22 and may be secured to midsole 22 by adhesive or other suitable means. Suitable materials for outsole 24 include rubber and carbon rubber, for example. Other suitable materials for outsole 24 will become readily apparent to those skilled in the art, given the benefit of this disclosure. In certain embodiments, sole assembly 14 may not include an outsole layer separate from midsole 22 but, rather, the outsole comprises a bottom surface of midsole 22 that provides the external traction surface of sole assembly 14.
As seen in
Polyurethane is stiffer and more wear-resistant than EVA, thus it will not break down as quickly as the EVA material. The EVA material, on the other hand, is lighter than the PU material, helping to reduce the overall weight of footwear 10, and is also more water resistant.
Upper layer 26 has a plurality of fingers 30 extending downwardly from a lower surface thereof about at least a portion of a perimeter thereof. As illustrated in
Lower layer 28 includes a raised central portion 32 and a flange 34 extending about the periphery of lower layer 28 defining a recess 35 about the periphery of lower layer 28. Fingers 30 extend into recess 35 about the periphery of raised central portion 32 and are seated on flange 34.
In the illustrated embodiment, raised central portion 32 includes a first portion 34 and a second portion 36. First portion 34 is positioned in midfoot portion 18 and forefoot portion 16 of lower layer 28 and second portion 36 is positioned in heel portion 20 of lower layer 28. In the illustrated embodiment, first portion 34 of lower layer 28 has a height greater than a height of second portion 36. Each of a plurality of ribs 38 extends outwardly along an upper surface of flange 34. Fingers 30 are seated in recess 35 on flange 34 adjacent first portion 34 and between selected adjacent ribs 38 about the periphery of lower layer 28.
Fingers 30, by extending downwardly about the periphery of lower layer 28 provide a stiffer and more wear-resistant area around lower layer 28, thereby providing improved support for footwear 10.
Another embodiment is illustrated in
In certain embodiments, the first material has a density and weight greater than the density and weight of the second material. In other embodiments, the second material has a resistance to moisture that is greater than the resistance to moisture of the first material. In other embodiments, the first material is more wear resistant than the second material. In certain embodiments, the first material is polyurethane (PU) and the second material is ethyl vinyl acetate (EVA).
Upper layer 46 has a plurality of fingers 50 extending downwardly from a lower surface thereof about at least a portion of a perimeter thereof. As illustrated in
In certain embodiments, a fluid-filled bag 54 is positioned between upper layer 46 and lower layer 48. Fluid-filled bag 54 may be filled with air or any other suitable fluid. In the illustrated embodiment, fluid-filled bag 54 is positioned in forefoot portion 16 of midsole 22. As seen in
A plurality of projections 60 may extend upwardly from the lower surface of recess 56 of lower layer 48, and are received in corresponding recesses formed in the lower surface of fluid-filled bag 54 (not shown). A plurality of recesses 62 is also formed in an upper surface of fluid-filled bag 54. When forming upper layer 46, fluid-filled bag 54 is positioned in a mold, and a plurality of locating pins (not shown) serve to register and align fluid-filled bag 54 in the proper position within the mold. The material, such as polyurethane, for example, used to form upper layer 46 is then poured into the mold over fluid-filled bag 54, and flows into recesses 62 and around the locating pins. Since the material flows about the locating pins, a plurality of apertures 64 remain in forefoot portion 16 of upper layer 46 when the upper layer 46 is removed from the mold.
In the illustrated embodiment, fingers 30 have a substantially rectangular cross-section. It is to be appreciated, however, that fingers 30 may have any desired cross-section and that other suitable cross-sections of fingers 30 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
In light of the foregoing disclosure of the invention and description of the preferred embodiments, those skilled in this area of technology will readily understand that various modifications and adaptations can be made without departing from the scope and spirit of the invention. All such modifications and adaptations are intended to be covered by the following claims.
