Boots – shoes – and leggings – Soles – Cushion
Reexamination Certificate
2002-05-09
2004-09-28
Stashick, Anthony (Department: 3728)
Boots, shoes, and leggings
Soles
Cushion
C036S03500R, C036S141000, C036S037000
Reexamination Certificate
active
06796056
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved cushioning system for athletic footwear which provides a large deflection for cushioning the initial impact of footstrike, a controlled stiffness response, a smooth transition to bottom-out and stability, and more specifically to a system which allows for customization of these response characteristics by adjustment of the orientation of a single bladder in a resilient foam material.
2. Description of Related Art
Basketball, tennis, running, and aerobics are but a few of the many popular athletic activities which produce a substantial impact on the foot when the foot strikes the ground. To cushion the strike force on the foot, as well as the leg and connecting tendons, the sole of shoes designed for such activities typically include several layers, including a resilient, shock absorbent layer such as a midsole and a ground contacting outer sole or outsole which provides both durability and traction.
The typical midsole uses one or more materials or components which affect the force of impact in two important ways, i.e., through shock absorption and energy dissipation. Shock absorption involves the attenuation of harmful impact forces to thereby provide enhanced foot protection. Energy dissipation is the dissemination of both impact and useful propulsive forces. Thus, a midsole with high energy dissipation characteristics generally has a relatively low resiliency and, conversely, a midsole with low energy dissipating characteristics generally has a relatively high resiliency. The optimum midsole should be designed with an impact response that takes into consideration both adequate shock absorption and sufficient resiliency.
One type of sole structure in which attempts have been made to design appropriate impact response are soles, or inserts for soles, that contain a bladder element of either a liquid or gaseous fluid. These bladder elements are either encapsulated in place during the foam midsole formation or dropped into a shallow, straight walled cavity and cemented in place, usually with a separate piece of foam cemented on top. Particularly successful gas filled structures are disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Marion F. Rudy, the contents of which are hereby incorporated by reference. An inflatable bladder or barrier member is formed of an elastomeric material having a multiplicity of preferably intercommunicating, fluid-containing chambers inflated to a relatively high pressure by a gas having a low diffusion rate through the bladder. The gas is supplemented by ambient air diffusing through the bladder to thereby increase the pressure therein and obtain a pressure that remains at or above its initial value over a period of years. (U.S. Pat. Nos. 4,340,626, 4,936,029 and 5,042,176 to Marion F. Rudy describe various diffusion mechanisms and are also hereby incorporated by reference.)
The pressurized, inflatable bladder insert is incorporated into the insole structure, in the '156 patent, by placement within a cavity below the upper, e.g., on top of a midsole layer and within sides of the upper or midsole. In the '945 patent, the inflatable bladder insert is encapsulated within a yieldable foam material, which functions as a bridging moderator filling in the irregularities of the bladder, providing a substantially smooth and contoured surface for supporting the foot and forming an easily handled structure for attachment to an upper. The presence of the moderating foam, however, detracts from the cushioning and perception benefits of the gas inflated bladder. Thus, when the inflated bladder is encapsulated in a foam midsole, the impact response characteristics of the bladder are hampered by the effect of the foam structure. Referring to FIG. 5 of the '945 patent for example, the cross-section of the midsole shows a series of tubes linked together to form the gas filled bladder. When the bladder is pressurized its tendency is to be generally round in cross-section. The spaces between those bladder portions are filled with foam. Because the foam-filled spaces include such sharp corners, the foam density in the midsole is uneven, i.e., the foam is of higher density in the corners and smaller spaces, and lower density along rounded or flatter areas of the bladder. Since foam has a stiffer response to compression, in the tighter areas with foam concentrations, the foam will dominate the cushioning response upon loading. So instead of a high deflection response, the response can be stiff due to the foam reaction. The cushioning effects of the bladder thus may be reduced due to the uneven concentrations of foam. In addition, the manufacturing techniques used to produce the sole structure formed by the combination of the foam midsole and inflated bladder must also be accommodating to both elements. For example, when encapsulating the inflatable bladder, only foams with relatively low processing temperatures can be used due to the susceptibility of the bladder to deform at high temperatures. The inflated bladder must also be designed with a thickness less than that of the midsole layer in order to allow for the presence of the foam encapsulating material completely therearound. Thus, there are manufacturing as well as performance constraints imposed in the foam encapsulation of an inflatable bladder.
A cushioning shoe sole component that includes a structure for adjusting the impact response of the component is disclosed in U.S. Pat. No. 4,817,304 to Mark G. Parker et al. The sole component of Parker et al. is a viscoelastic unit formed of a gas containing bladder and an elastomeric yieldable outer member encapsulating the bladder. The impact resistance of the viscoelastic unit is adjusted by forming a gap in the outer member at a predetermined area where it is desired to have the bladder predominate the impact response. The use of the gap provides an adjustment of the impact response, but the adjustment is localized to the area of the gap. The '304 patent does not disclose a way of tuning the impact response to optimize the response over the time of footstrike through the appropriate structuring of both the bladder and encapsulating material.
A cushioning system for a shoe sole which uses a bladder connected only along its perimeter and supported in an opening in resilient foam material, is disclosed in U.S. Pat. No. 5,685,090 to Tawney et al., which is hereby incorporated by reference. The bladder of Tawney et al. has generally curved upper and lower major surfaces and a sidewall that extends outward from each major surface. The angled sidewalls form a horizontally orientated V-shape in cross-section, which fits into a correspondingly shaped groove in the opening in the surrounding resilient foam material. Portions of the top and bottom of the bladder are not covered with the foam material. By forming the bladder without internal connections between the top and bottom surfaces, and exposing portions of the top and bottom surfaces, the feel of the bladder is maximized. However, the '090 patent does not disclose a way of tuning the impact response through design of both the bladder and foam material.
One type of prior art construction concerns air bladders employing an open-celled foam core as disclosed in U.S. Pat. Nos. 4,874,640 and 5,235,715 to Donzis. These cushioning elements do provide latitude in their design in that the open-celled foam cores allow for a variety of shapes of the bladder. However, bladders with foam core tensile members have the disadvantage of unreliable bonding of the core to the barrier layers. One of the main disadvantages of this construction is that the foam core defines the shape of the bladder and thus must necessarily function as a cushioning member at footstrike which detracts from the superior cushioning properties of air alone. The reason for this is that in order to withstand the high inflation pressures associated with such air bladders, the foam core must be of a high strength which requires the use of
Banner & Witcoff , Ltd.
Nike Inc.
Stashick Anthony
LandOfFree
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