Patent Description:
Sole structures generally include a layered arrangement extending between a ground surface and the upper. One layer of the sole structure includes an outsole that provides abrasion-resistance and traction with the ground surface. The outsole may be formed from rubber or other materials that impart durability and wear-resistance, as well as enhance traction with the ground surface. Another layer of the sole structure includes a midsole disposed between the outsole and the upper. The midsole provides cushioning for the foot and may be partially formed from a polymer foam material that compresses resiliently under an applied load to cushion the foot by attenuating ground-reaction forces. The midsole may additionally or alternatively incorporate a fluid-filled bladder to increase durability of the sole structure, as well as to provide cushioning to the foot by compressing resiliently under an applied load to attenuate ground-reaction forces. Sole structures may also include a comfort-enhancing insole or a sockliner located within a void proximate to the bottom portion of the upper and a strobel attached to the upper and disposed between the midsole and the insole or sockliner.

Midsoles employing fluid-filled bladders typically include a bladder formed from two barrier layers of polymer material that are sealed or bonded together. The fluid-filled bladders are pressurized with a fluid such as air, and may incorporate tensile members within the bladder to retain the shape of the bladder when compressed resiliently under applied loads, such as during athletic movements. Generally, bladders are designed with an emphasis on balancing support for the foot and cushioning characteristics that relate to responsiveness as the bladder resiliently compresses under an applied load.

Document <CIT> describes a sole structure including a midsole layer with a lower surface having a first recess that has an outer periphery spaced inward of an outer periphery of the midsole layer, and a peripheral bonding region between the outer periphery of the midsole layer and the outer periphery of the first recess. A sole plate has an upper surface with a second recess forming a cavity with the first recess between the sole plate and the midsole layer. The upper surface of the sole plate has a peripheral bonding region between an outer periphery of the sole plate and an outer periphery of the second recess. A bladder nests in the cavity with a contoured upper surface inward of the peripheral bonding region of the midsole layer and a contoured lower surface inward of the peripheral bonding region of the sole plate.

In one configuration, a bladder for an article of footwear is provided and includes an inner chamber having a first interior void and a tensile member disposed within the first interior void, the inner chamber having a constant thickness. The bladder additionally includes a peripheral chamber surrounding the inner chamber and including a second interior void, the peripheral chamber having a variable thickness that is greater than the constant thickness of the inner chamber.

Implementations of the disclosure may include one or more of the following optional features. In some implementations, the peripheral chamber may include one or more deformation zones. The deformation zones may include substantially straight sides of the peripheral chamber. Additionally or alternatively, the deformation zones may be progressively defined along a length of the bladder.

The peripheral chamber may include a posterior segment disposed at a first end of the bladder and an anterior segment disposed at a second end of the bladder, the posterior segment having a greater thickness than the anterior segment. Further, the peripheral chamber may include one or more elongate segments connecting the anterior segment and the posterior segment, the variable thickness of the bladder continuously tapering from the posterior segment to the anterior segment.

A first barrier layer and a second barrier layer may cooperate to define each of the inner chamber and the peripheral chamber. The first barrier layer and the second barrier layer may be attached to the tensile member in the inner chamber.

The inner chamber may be curved along a lengthwise direction of the bladder. Additionally or alternatively, the inner chamber may be straight along a widthwise direction of the bladder.

In another configuration, a bladder for an article of footwear is provided and includes an inner chamber having a constant thickness and a peripheral chamber completely surrounding and in fluid communication with the inner chamber, the peripheral chamber having a greater thickness than the inner chamber and including one or more deformation zones.

Implementations of the disclosure may include one or more of the following optional features. In some implementations, the one or more deformation zones may include a plurality of deformation zones extending along the peripheral chamber. The one or more deformation zones may be defined by substantially straight sides of the peripheral chamber. Additionally or alternatively, the deformation zones may be progressively defined along a length of the bladder.

The peripheral chamber may include a posterior segment disposed at a first end of the bladder and an anterior segment disposed at a second end of the bladder, the posterior segment having a greater thickness than the anterior segment. Additionally or alternatively, the peripheral chamber may include one or more elongate segments connecting the anterior segment and the posterior segment, the thickness of the bladder continuously tapering from the posterior segment to the anterior segment.

A first barrier layer and a second barrier layer may cooperate to define each of the inner chamber and the peripheral chamber. Further, the first barrier layer and the second barrier layer may be attached to a tensile member in the inner chamber.

Referring to <FIG>, an article of footwear <NUM> includes a sole structure <NUM> and an upper <NUM> attached to the sole structure <NUM>. The article of footwear <NUM>, and components thereof, may be described as including an anterior end <NUM> associated with a forward-most point of the footwear <NUM>, and a posterior end <NUM> corresponding to a rearward-most point of the footwear <NUM>. As shown in <FIG>, a longitudinal axis A<NUM> of the footwear <NUM> extends along a length of the footwear <NUM> from the anterior end <NUM> to the posterior end <NUM>. The longitudinal axis A<NUM> generally divides the footwear <NUM> into a lateral side <NUM> and a medial side <NUM>. Accordingly, the lateral side <NUM> and the medial side <NUM> respectively correspond with opposite sides of the footwear <NUM> and extend from the anterior end <NUM> to the posterior end <NUM>.

The article of footwear <NUM> may be divided into one or more regions along the longitudinal axis A<NUM>. The regions may include a forefoot region <NUM>, a mid-foot region <NUM>, and a heel region <NUM>. The forefoot region <NUM> may correspond with toes and joints connecting metatarsal bones with phalanx bones of a foot. The mid-foot region <NUM> may correspond with an arch area of the foot, and the heel region <NUM> may correspond with rear regions of the foot, including a calcaneus bone.

The article of footwear <NUM>, and more particularly, the sole structure <NUM>, may be further described as including a peripheral region <NUM> and an interior region <NUM>, as indicated by the dashed line in <FIG>. The peripheral region <NUM> is generally described as being a region between the interior region <NUM> and an outer perimeter of the sole structure <NUM>. Particularly, the peripheral region <NUM> extends from the forefoot region <NUM> to the heel region <NUM> along each of the lateral side <NUM> and the medial side <NUM>, and wraps around each of the forefoot region <NUM> and the heel region <NUM>. The interior region <NUM> is circumscribed by the peripheral region <NUM>, and extends from the forefoot region <NUM> to the heel region <NUM> along a central portion of the sole structure <NUM>. Accordingly, each of the forefoot region <NUM>, the mid-foot region <NUM>, and the heel region <NUM> may be described as including the peripheral region <NUM> and the interior region <NUM>.

With reference to <FIG>, the sole structure <NUM> includes a midsole <NUM> configured to provide cushioning characteristics to the sole structure <NUM>, and an outsole <NUM> configured to provide a ground-engaging surface of the article of footwear <NUM>. Unlike conventional sole structures, which include unitary midsoles formed of a single material, the midsole <NUM> is formed compositely and includes multiple subcomponents. For example, the midsole <NUM> includes a bladder <NUM> and an upper cushion <NUM> stacked upon the bladder <NUM>. Additionally, the midsole <NUM> may include a peripheral support member <NUM> surrounding an outer periphery of the bladder <NUM> and the upper cushion <NUM>. The subcomponents <NUM>, <NUM>, <NUM> are assembled and secured to each other using various methods of bonding, including adhesively bonding and melding, for example.

With reference to <FIG>, the bladder <NUM> of the midsole <NUM> includes an opposing pair of barrier layers 112a, 112b, which can be joined to each other along a peripheral seam <NUM> to form a peripheral chamber <NUM> and an inner chamber <NUM>. As shown, the barrier layers 112a, 112b include a first, upper barrier layer 112a and a second, lower barrier layer 112b.

As used herein, the term "barrier layer" (e.g., barrier layers 112a, 112b) encompasses both monolayer and multilayer films. In some embodiments, one or both of the barrier layers 112a, 112b are each produced (e.g., thermoformed or blow molded) from a monolayer film (a single layer). In other embodiments, one or both of the barrier layers 112a, 112b are each produced (e.g., thermoformed or blow molded) from a multilayer film (multiple sublayers). In either aspect, each layer or sublayer can have a film thickness ranging from about <NUM> micrometers to about be about <NUM> millimeter. In further embodiments, the film thickness for each layer or sublayer can range from about <NUM> micrometers to about <NUM> micrometers. In yet further embodiments, the film thickness for each layer or sublayer can range from about <NUM> micrometer to about <NUM> micrometers.

One or both of the barrier layers 112a, 112b can independently be transparent, translucent, and/or opaque. As used herein, the term "transparent" for a barrier layer and/or a fluid-filled chamber means that light passes through the barrier layer in substantially straight lines and a viewer can see through the barrier layer. In comparison, for an opaque barrier layer, light does not pass through the barrier layer and one cannot see clearly through the barrier layer at all. A translucent barrier layer falls between a transparent barrier layer and an opaque barrier layer, in that light passes through a translucent layer but some of the light is scattered so that a viewer cannot see clearly through the layer.

The barrier layers 112a, 112b can each be produced from an elastomeric material that includes one or more thermoplastic polymers and/or one or more cross-linkable polymers. In an aspect, the elastomeric material can include one or more thermoplastic elastomeric materials, such as one or more thermoplastic polyurethane (TPU) copolymers, one or more ethylene-vinyl alcohol (EVOH) copolymers, and the like.

Examples of suitable isocyanates for producing the polyurethane copolymer chains include diisocyanates, such as aromatic diisocyanates, aliphatic diisocyanates, and combinations thereof. Examples of suitable aromatic diisocyanates include toluene diisocyanate (TDI), TDI adducts with trimethyloylpropane (TMP), methylene diphenyl diisocyanate (MDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated xylene diisocyanate (HXDI), naphthalene <NUM>,<NUM>-diisocyanate (NDI), <NUM>,<NUM>-tetrahydronaphthalene diisocyanate, para-phenylene diisocyanate (PPDI), <NUM>,<NUM>' - dimethyldiphenyl-<NUM>, <NUM>' -diisocyanate (DDDI), <NUM>,<NUM> '-dibenzyl diisocyanate (DBDI), <NUM>-chloro-<NUM>,<NUM>-phenylene diisocyanate, and combinations thereof. In some embodiments, the copolymer chains are substantially free of aromatic groups.

In another aspect, the polymeric layer can be formed of one or more of the following: EVOH copolymers, poly(vinyl chloride), polyvinylidene polymers and copolymers (e.g., polyvinylidene chloride), polyamides (e.g., amorphous polyamides), amide-based copolymers, acrylonitrile polymers (e.g., acrylonitrile-methyl acrylate copolymers), polyethylene terephthalate, polyether imides, polyacrylic imides, and other polymeric materials known to have relatively low gas transmission rates. Blends of these materials as well as with the TPU copolymers described herein and optionally including combinations of polyimides and crystalline polymers, are also suitable.

The barrier layers 112a, 112b may include two or more sublayers (multilayer film) such as shown in <CIT> and <CIT>. In embodiments where the barrier layers 112a, 112b include two or more sublayers, examples of suitable multilayer films include microlayer films, such as those disclosed in <CIT>. In further embodiments, barrier layers 112a, 112b may each independently include alternating sublayers of one or more TPU copolymer materials and one or more EVOH copolymer materials, where the total number of sublayers in each of barrier layers 112a, 112b includes at least four (<NUM>) sublayers, at least ten (<NUM>) sublayers, at least twenty (<NUM>) sublayers, at least forty (<NUM>) sublayers, and/or at least sixty (<NUM>) sublayers.

The bladder <NUM> can be produced from barrier layers 112a, 112b using any suitable technique, such as thermoforming (e.g. vacuum thermoforming), blow molding, extrusion, injection molding, vacuum molding, rotary molding, transfer molding, pressure forming, heat sealing, casting, low-pressure casting, spin casting, reaction injection molding, radio frequency (RF) welding, and the like. In an aspect, barrier layers 112a, 112b can be produced by co-extrusion followed by vacuum thermoforming to produce an inflatable bladder <NUM>, which can optionally include one or more valves (e.g., one way valves) that allows bladder <NUM> to be filled with the fluid (e.g., gas).

The chambers <NUM>, <NUM> of the bladder <NUM> can be provided in a fluid-filled (e.g., as provided in footwear <NUM>) or in an unfilled state. The chambers <NUM>, <NUM> can be filled to include any suitable fluid, such as a gas or liquid. In an aspect, the gas can include air, nitrogen (N<NUM>), or any other suitable gas. The fluid provided to the chambers <NUM>, <NUM> can result in the bladder <NUM> being pressurized. Alternatively, the fluid provided to the chambers <NUM>, <NUM> can be at atmospheric pressure such that the bladder <NUM> is not pressurized but, rather, simply contains a volume of fluid at atmospheric pressure. In other aspects, the chambers <NUM>, <NUM> can alternatively include other media, such as pellets, beads, ground recycled material, and the like (e.g., foamed beads and/or rubber beads).

The barrier layers 112a, 112b desirably have a low gas transmission rate to preserve its retained gas pressure. In some embodiments, the barrier layers 112a, 112b have a gas transmission rate for nitrogen gas that is at least about ten (<NUM>) times lower than a nitrogen gas transmission rate for a butyl rubber layer of substantially the same dimensions. In an aspect, the barrier layers 112a, 112b have a nitrogen gas transmission rate of <NUM> cubic-centimeter/square-meter•atmosphere•day (cm<NUM>/m<NUM>•atm•day) or less for an average film thickness of <NUM> micrometers (based on thicknesses of barrier layers 112a, 112b). In further aspects, the transmission rate is <NUM><NUM>/m<NUM>•atm•day or less, <NUM><NUM>/m<NUM>•atm•day or less, or <NUM><NUM>/m<NUM>•atm•day or less.

In some implementations, the upper barrier layer 112a and the lower barrier layer 112b cooperate to define a geometry (e.g., shape, thicknesses, width, and lengths) of the bladder <NUM>. For example, the barrier layers 112a, 112b may be joined together along the peripheral seam <NUM> to define an outer periphery of the bladder <NUM> and to seal the fluid (e.g., air) within the peripheral chamber <NUM> and the inner chamber <NUM>. As shown in <FIG>, a length of the bladder <NUM> extends continuously from a first end <NUM> disposed at the anterior end <NUM> of the footwear <NUM> to a second end <NUM> disposed at the posterior end <NUM> of the footwear <NUM>.

The peripheral chamber <NUM> is formed in the peripheral region <NUM> of the bladder <NUM> and extends continuously and uninterrupted along the outer periphery of the bladder <NUM>. As shown in <FIG>, the barrier layers 112a, 112b are spaced apart from each other in the peripheral region <NUM> to define the peripheral chamber <NUM>. Particularly, the interior surfaces of the barrier layers 112a, 112b are separated from each other such that the space between the barrier layers 112a defines an interior void <NUM> of the peripheral chamber <NUM>, while a distance across exterior surfaces of the barrier layers 112a, 112b defines thicknesses T<NUM> of the peripheral chamber <NUM>. As shown, the upper and lower barrier layers 112a cooperate to provide the peripheral chamber <NUM> with a tubular shape having a greater thickness T<NUM> than the inner chamber <NUM>. In other words, the peripheral chamber <NUM> forms a bulbous or distended portion of the bladder <NUM> extending continuously and uninterrupted around the entire perimeter of the bladder <NUM>.

Although the peripheral chamber <NUM> is continuously formed around the perimeter of the bladder <NUM>, the peripheral chamber <NUM> may be described as including a plurality of segments 128a-128d each corresponding with an end <NUM>, <NUM> or side <NUM>, <NUM> of the bladder <NUM>. For example, <FIG> shows that the peripheral chamber <NUM> includes an anterior segment 128a disposed at the first end <NUM> of the bladder <NUM>, a posterior segment 128b disposed at the second end <NUM> of the bladder <NUM>, a lateral side segment 128c extending continuously along the lateral side <NUM> of the bladder <NUM>, and a medial side segment 128d extending continuously along the medial side <NUM> of the bladder <NUM>.

With reference to <FIG> and <FIG>, the anterior segment 128a extends along an arcuate path around the first end <NUM> of the bladder <NUM> from a first end 129a on the lateral side <NUM> of the bladder <NUM> to a second end 130a on the medial side <NUM> of the bladder <NUM>. The anterior segment 128a defines a first thickness T<NUM>-<NUM> of the peripheral chamber <NUM> at the first end <NUM>. The posterior segment 128b extends along an arcuate path around the second end <NUM> of the bladder <NUM> from a first end 129b disposed on the lateral side <NUM> to a second end 130b disposed on the medial side <NUM>. The posterior segment 128b defines a second thickness T<NUM>-<NUM> of the peripheral chamber <NUM>. The second thickness T<NUM>-<NUM> is greater than the first thickness T<NUM>-<NUM> such that the peripheral chamber <NUM> is thicker at the second end <NUM> than at the first end <NUM>.

The anterior segment 128a and the posterior segment 128b of the peripheral chamber <NUM> are connected by a pair of elongate side segments 128c, 128d that each extend along the length of the bladder from the first end <NUM> to the second end <NUM>. With reference to <FIG>, <FIG> and <FIG>, a first one of the side segments 128c includes a lateral side segment 128c extending continuously along the lateral side from the first end 129a of the anterior segment 128a to the first end 129b of the posterior segment 128b. Generally, the thickness of the peripheral chamber <NUM> tapers continuously along each of the side segments 128c, 128d from the second thickness T<NUM>-<NUM> at the second end <NUM> to the first thickness T<NUM>-<NUM> at the first end <NUM>.

As indicated in <FIG>, the cross-sectional views of <FIG> are taken in series along the length of the bladder <NUM> and illustrate the progressive increase in the thickness T<NUM> of the peripheral chamber <NUM> from the anterior segment 128a to the posterior segment 128b. For example, <FIG> is a cross-sectional view taken across the bladder <NUM> where the side segments 128c, 128d connect to the ends 129a, 130a of the anterior segment 128a. Here, each of the side segments 128c, 128d has the same thickness T<NUM>-<NUM> as the anterior segment 128a. <FIG> are cross-sectional views taken along intermediate portions (i.e., between the anterior segment 128a and posterior segment 128b) of the bladder <NUM>, as indicated in <FIG>. As shown, the intermediate portions of the side segments 128c, 128d include thicknesses T<NUM>-<NUM> (<FIG>), T<NUM>-<NUM> (<FIG>), T<NUM>-<NUM> (<FIG>), T<NUM>-<NUM> (<FIG>) that progressively and continuously increase along the length of the bladder <NUM> in a direction toward the heel region <NUM>. <FIG> shows a cross-sectional view of the bladder <NUM> taken where the side segments 128c, 128d connect to the ends 129b, 130b of the posterior segment 128b. Accordingly, the side segments 128c, 128d have the same thickness T<NUM>-<NUM> as the posterior segment 128b.

As set forth above, the barrier layers 112a, 112b cooperate to provide the peripheral chamber <NUM> with a tubular shape enclosing a fluid-filled interior void <NUM>. As shown in <FIG>, at least one of the upper barrier layer 112a and the lower barrier layer 112b may define one or more deformation zones 131a-131c along the peripheral chamber <NUM>. In the illustrated example, the peripheral chamber <NUM> includes a first deformation zone 131a extending along an outer portion of the peripheral chamber <NUM> adjacent to the peripheral seam <NUM>, a second deformation zone 131b extending along an inner portion of the peripheral chamber <NUM> adjacent to the inner chamber <NUM>, and a third deformation zone 131c extending along an upper portion of the peripheral chamber <NUM> and connecting the first deformation zone 131a and the second deformation zone 131b.

In the illustrated example, the portion of the upper barrier layer 112a forming the upper portion of the peripheral chamber <NUM> includes deformation zones 131a-131c formed as a plurality of connected sides of the peripheral chamber <NUM>. In other words, at least a portion of the peripheral chamber <NUM> may have a polygonal shape defined by the deformation zones 131a-131c. As shown in the figures, the deformation zones 131a-131c may be progressively formed along a direction from the first end <NUM> of the bladder <NUM> to the second end <NUM> of the bladder <NUM>. For instance, the deformation zones 131a-131c may have slight curvature and be substantially continuous in portions of the peripheral chamber <NUM> in the forefoot region (<FIG>). Conversely, the deformation zones 131a-131c may be substantially flat with clearly defined transitions in the portions of the peripheral chamber <NUM> in the heel region (<FIG>).

In use, the deformation zones 131a-131c provide expansion regions along the peripheral chamber <NUM>, such that when the bladder <NUM> is compressed and the pressure within the interior void <NUM> of the peripheral chamber <NUM> increases, the upper barrier layer 112a can progressively deform to accommodate or absorb the pressure increase. The progressive definition of the deformation zones 131a-131c along the lengths of the side segments 128c, 128d provides the heel region <NUM> with a greater degree of pressure compensation than the forefoot region <NUM> and mid-foot region <NUM> to accommodate forces associated with a heel strike.

Referring now to <FIG>, the inner chamber <NUM> of the bladder <NUM> is formed within the interior region <NUM> of the bladder <NUM>, is continuously and completely surrounded by the peripheral chamber <NUM>, and is in fluid communication with the peripheral chamber <NUM>. Here, the inner chamber <NUM> extends continuously along a length of the bladder <NUM> from the anterior segment 128a of the peripheral chamber <NUM> disposed at the first end <NUM> to the posterior segment 128b of the peripheral chamber disposed at the second end <NUM> of the bladder <NUM>. As shown in <FIG>, the inner chamber <NUM> also extends continuously and uninterrupted between the lateral side segment 128c and the medial side segment 128d along the entire length of the inner chamber <NUM>. Accordingly, the inner chamber <NUM> may be described as filling the entire space (i.e., the interior region <NUM>) surrounded by the peripheral chamber <NUM>.

As shown in <FIG>, the inner chamber <NUM> is formed by portions of the barrier layers 112a, 112b that are spaced apart from each other in the interior region <NUM>. The space between the barrier layers 112a, 112b, forms an interior void <NUM> of the inner chamber <NUM>. The interior void <NUM> of the inner chamber <NUM> receives a tensile element <NUM> therein. The tensile element <NUM> may include a series of tensile strands or elements <NUM> extending between an upper tensile sheet 136a and a lower tensile sheet 136b. The upper tensile sheet 136a may be attached to the interior surface of the upper barrier layer 112a while the lower tensile sheet 136b may be attached to the interior surface of the lower barrier layer 112b. In this manner, when the inner chamber <NUM> receives a pressurized fluid, the tensile strands <NUM> of the tensile element <NUM> are placed in tension. Because the upper tensile sheet 136a is attached to the upper barrier layer 112a and the lower tensile sheet 136b is attached to the lower barrier layer 112b, the tensile strands <NUM> retain a desired shape of the inner chamber <NUM> when the pressurized fluid is injected into the interior void <NUM>.

With continued reference to <FIG>, when the bladder <NUM> is inflated, the tensile element <NUM> provides the inner chamber <NUM> with a constant thickness T<NUM> extending along the length and width of the inner chamber <NUM>. The thickness T<NUM> of the inner chamber <NUM> is less than the thicknesses T<NUM>-<NUM>-T<NUM>-<NUM> of the peripheral chamber <NUM>. As shown, the portions of the upper and lower barrier layers 112a, 112b forming the inner chamber <NUM> are inwardly offset from portions the barrier layers 112a, <NUM> forming the peripheral chamber <NUM>. In other words, the portions of the upper and lower barrier layers 112a, 112b forming the peripheral chamber <NUM> protrude from the portions of the upper and lower barrier layers 112a, 112b forming the inner chamber <NUM>.

The inner chamber <NUM> and the peripheral chamber <NUM> cooperate to define a pair of pockets or cavities 138a, 138b on opposite sides of the bladder <NUM>. Particularly, the bladder <NUM> includes an upper pocket 138a defined by the upper barrier layer 112a on a top side of the bladder <NUM> and a lower pocket 138b defined by the lower barrier layer 112b. A bottom surface of the upper pocket 138a is defined by the portion of the upper barrier layer 112a extending along the inner chamber <NUM> and an outer periphery of the upper pocket 138a is defined by the portion of the upper barrier layer 112a forming an inner portion (i.e., facing the interior region <NUM>) of the peripheral chamber <NUM>. Conversely, a top surface of the lower pocket 138b is defined by the portion of the lower barrier layer 112b extending along the inner chamber <NUM> and an outer periphery of the lower pocket 138b is defined by the portion of the lower barrier layer 112b forming an inner portion (i.e., facing the interior region <NUM>) of the peripheral chamber <NUM>.

In addition to retaining the barrier layer 112a, 112b to define the thickness T<NUM> of the inner chamber <NUM>, the tensile element <NUM> may be configured to impart an overall shape or contour to the inner chamber <NUM>. As shown in <FIG>, the inner chamber <NUM> is substantially straight along the lateral direction from the lateral side <NUM> to the medial side <NUM>. However, as shown in <FIG>, the inner chamber <NUM> may have an arcuate shape extending along the length of the bladder <NUM>. Thus, although the thickness T<NUM> of the inner chamber <NUM> is substantially constant, the shape of the inner chamber <NUM> may curve from the first end <NUM> to the second end <NUM>. In the illustrated example, the inner chamber <NUM> has an "upward" curvature along the longitudinal direction, such that the upper barrier layer 112a is concave and the lower barrier layer 112b is convex. In some examples, a radius R<NUM> of curvature of the inner chamber <NUM> is substantially constant along the entire length of the inner chamber <NUM>.

In the illustrated example of the bladder <NUM>, the peripheral chamber <NUM> and the inner chamber <NUM> are integrally formed by the barrier layers 112a, 112b. Accordingly, the interior void <NUM> of the peripheral chamber <NUM> is in fluid communication with the interior void <NUM> of the inner chamber <NUM>, such that the entire bladder <NUM> has a uniform pressure. In use, the inner chamber <NUM> may be compressed between the ground surface and a plantar surface of the foot during an impact with the ground surface. When compressed, the pressure of the fluid within the bladder <NUM> increases and the fluid within the inner chamber <NUM> is displaced from the interior void <NUM> of the inner chamber <NUM> to the interior void <NUM> of the peripheral chamber <NUM>. As set forth above, the portions of the barrier layers 112a, 112b forming the peripheral chamber <NUM> may include one or more deformation zones 131a-131c. When the fluid pressure within the interior void <NUM> of the peripheral chamber increases and the fluid of the bladder <NUM> moves into the interior void <NUM>, the deformation zones 131a-131c of the peripheral chamber <NUM> are biased outwardly to accommodate the pressure change, thereby providing a damping effect along the peripheral region of the sole structure <NUM>.

With continued reference to <FIG>, the upper cushion <NUM> of the midsole is formed of a resilient polymeric material and is configured to be received within the upper pocket 138a of the bladder <NUM>. As shown in <FIG> and <FIG>, the upper cushion <NUM> extends continuously from a first end <NUM> disposed at the first end <NUM> of the bladder <NUM> to a second end <NUM> disposed at the second end <NUM> of the bladder <NUM>. The upper cushion <NUM> further includes a top surface <NUM> defining a footbed of the sole structure <NUM> and a bottom surface <NUM> formed on an opposite side of the upper cushion <NUM> from the top surface <NUM>. A distance between the top surface <NUM> and the bottom surface defines a thickness T<NUM> of the upper cushion <NUM>. The upper cushion <NUM> further includes a peripheral side surface <NUM> extending from the top surface <NUM> to the bottom surface <NUM>, which defines an outer peripheral profile of the upper cushion <NUM>.

When the sole structure <NUM> is assembled, the upper cushion <NUM> is received within the upper pocket 138a such that the bottom surface <NUM> faces the inner chamber <NUM> and the peripheral side surface <NUM> mates with the peripheral chamber <NUM>. As shown in <FIG>, the peripheral side surface <NUM> may include a concave channel <NUM> configured to mate with the inner portion of the peripheral chamber <NUM>. In some examples, the upper cushion <NUM> may be directly disposed within the upper pocket 138a, whereby the upper cushion <NUM> is attached directly to the inner chamber <NUM> and the peripheral chamber <NUM>. However, in the illustrated example, the upper cushion <NUM> is configured as a sockliner or insole, and is disposed within an interior void <NUM> of the upper <NUM>, such that a strobel <NUM> of the upper <NUM> is disposed between the bladder <NUM> and the upper cushion <NUM>.

As described above, the upper cushion <NUM> is formed of a resilient polymeric material, such as foam or rubber, to impart properties of cushioning, responsiveness, and energy distribution to the foot of the wearer. Example resilient polymeric materials may include those based on foaming or molding one or more polymers, such as one or more elastomers (e.g., thermoplastic elastomers (TPE)). The one or more polymers may include aliphatic polymers, aromatic polymers, or mixtures of both; and may include homopolymers, copolymers (including terpolymers), or mixtures of both.

In further aspects, the one or more polymers may include one or more polyamide copolymers (e.g., polyamide-polyether copolymers) and/or one or more polyurethanes (e.g., crosslinked polyurethanes and/or thermoplastic polyurethanes). Examples of suitable polyurethanes include those discussed above for barrier layers 112a, 112b. Alternatively, the one or more polymers may include one or more natural and/or synthetic rubbers, such as butadiene and isoprene.

When the resilient polymeric material is a foamed polymeric material, the foamed material may be foamed using a physical blowing agent which phase transitions to a gas based on a change in temperature and/or pressure, or a chemical blowing agent which forms a gas when heated above its activation temperature. For example, the chemical blowing agent may be an azo compound such as azodicarbonamide, sodium bicarbonate, and/or an isocyanate.

The midsole <NUM> further includes the peripheral support member <NUM> connecting the peripheral chamber <NUM> to the upper <NUM> along the entire periphery of the footwear <NUM>. The peripheral support member <NUM> includes one or more of the elastomeric materials discussed above with respect to the barrier layers 112a, 112b. As shown in <FIG>, the peripheral support member <NUM> includes a lower portion <NUM> attached to the outer portion (i.e., facing away from the interior region <NUM>) of the peripheral chamber <NUM>. The peripheral support member <NUM> also includes an upper portion <NUM> attached to the exterior of the upper <NUM>. Thus, the peripheral support member <NUM> is configured to provide lateral stability between the upper <NUM> and the bladder <NUM> along the outer periphery of the footwear <NUM>.

The outsole <NUM> of the sole structure <NUM> may be formed as an over-molded component covering the entire lower barrier layer 112b of the bladder <NUM>, thereby providing the sole structure <NUM> with an extra layer along the ground surface. As shown in <FIG>, the outsole <NUM> includes an inner surface <NUM> configured to attach to the lower barrier layer 112b of the bladder <NUM>, and an outer surface <NUM> formed on an opposite side of the outsole <NUM> and configured to provide a ground-contacting surface of the sole structure <NUM>. The outsole <NUM> also includes an interior portion <NUM> configured to mate with the lower pocket 138b of the bladder <NUM>, and a peripheral channel <NUM> configured to receive the lower portion of the peripheral chamber <NUM>.

The upper <NUM> includes interior surfaces that define an interior void <NUM> configured to receive and secure a foot for support on the sole structure <NUM>. The upper <NUM> may be formed from one or more materials that are stitched or adhesively bonded together to form the interior void <NUM>. Suitable materials of the upper may include, but are not limited to, mesh, textiles, foam, leather, and synthetic leather. The materials may be selected and located to impart properties of durability, air-permeability, wear-resistance, flexibility, and comfort.

With reference to <FIG>, in some examples the upper <NUM> includes the strobel <NUM> enclosing a bottom portion of the interior void <NUM>. Stitching or adhesives may secure the strobel to the upper <NUM>. As set forth above, the strobel <NUM> of the upper <NUM> may be disposed between the bladder <NUM> and the upper cushion <NUM> when the article of footwear <NUM> is assembled.

Claim 1:
A bladder (<NUM>) for an article of footwear (<NUM>), the bladder (<NUM>) comprising;
an inner chamber (<NUM>) including a first interior void and a tensile member (<NUM>) disposed within the first interior void, the inner chamber (<NUM>) having a constant thickness (T<NUM>); and
a peripheral chamber (<NUM>) surrounding the inner chamber (<NUM>) and including a second interior void, the peripheral chamber (<NUM>) having a variable thickness that is greater than the constant thickness of the inner chamber (<NUM>).