Patent Application
20090288312
Articles of footwear generally include two primary elements, an upper and a sole structure. The upper is formed from a variety of material elements (e.g., textiles, foam, leather, and synthetic leather) that are stitched or adhesively bonded together to form a void on the interior of the footwear for comfortably and securely receiving a foot. An ankle opening through the material elements provides access to the void, thereby facilitating entry and removal of the foot from the void. In addition, a lace is utilized to modify the dimensions of the void and secure the foot within the void.
The sole structure is located adjacent to a lower portion of the upper and is generally positioned between the foot and the ground. In many articles of footwear, including athletic footwear, the sole structure conventionally incorporates an insole, a midsole, and an outsole. The insole is a thin compressible member located within the void and adjacent to a lower surface of the void to enhance footwear comfort. The midsole, which may be secured to a lower surface of the upper and extends downward from the upper, forms a middle layer of the sole structure. In addition to attenuating ground reaction forces (i.e., providing cushioning for the foot), the midsole may limit foot motions or impart stability, for example. The outsole, which may be secured to a lower surface of the midsole, forms the ground-contacting portion of the footwear and is usually fashioned from a durable and wear-resistant material that includes texturing to improve traction.
The conventional midsole is primarily formed from a foamed polymer material, such as polyurethane or ethylvinylacetate, that extends throughout a length and width of the footwear. In some articles of footwear, the midsole may include a variety of additional footwear elements that enhance the comfort or performance of the footwear, including plates, moderators, fluid-filled chambers, lasting elements, or motion control members. In some configurations, any of these additional footwear elements may be located between the midsole and either of the upper and outsole, embedded within the midsole, or encapsulated by the foamed polymer material of the midsole, for example. Although many conventional midsoles are primarily formed from a foamed polymer material, fluid-filled chambers or other non-foam structures may form a majority of some midsole configurations.
A fluid-filled chamber is disclosed as including an outer barrier, a tensile member, and a fluid. The barrier is formed of a polymer material that defines an interior void. The tensile member is located within the interior void and bonded to opposite sides of the interior void. The tensile member is formed from a textile element that includes a pair of spaced layers joined by a plurality of connecting members. In some configurations, an edge of the tensile member may have a finished configuration or the tensile member may be contoured. The fluid is located within the interior void and is pressurized to place an outward force upon the barrier and induce tension in at least a portion of the tensile member.
A method of manufacturing a fluid-filled chamber is also disclosed. The method includes forming a textile tensile member with at least one contoured surface or a finished edge. The tensile member is located within a polymer barrier and bonded to opposite sides of the barrier.
The advantages and features of novelty characterizing aspects of the invention are pointed out with particularity in the appended claims. To gain an improved understanding of the advantages and features of novelty, however, reference may be made to the following descriptive matter and accompanying figures that describe and illustrate various configurations and concepts related to the invention.
The foregoing Summary and the following Detailed Description will be better understood when read in conjunction with the accompanying figures.
The following discussion and accompanying figures disclose various configurations of fluid-filled chambers and methods for manufacturing the chambers. Although the chambers are disclosed with reference to footwear having a configuration that is suitable for running, concepts associated with the chambers may be applied to a wide range of athletic footwear styles, including basketball shoes, cross-training shoes, football shoes, golf shoes, hiking shoes and boots, ski and snowboarding boots, soccer shoes, tennis shoes, and walking shoes, for example. Concepts associated with the chambers may also be utilized with footwear styles that are generally considered to be non-athletic, including dress shoes, loafers, and sandals. In addition to footwear, the chambers may be incorporated into other types of apparel and athletic equipment, including helmets, gloves, and protective padding for sports such as football and hockey. Similar chambers may also be incorporated into cushions and other compressible structures utilized in household goods and industrial products. Accordingly, chambers incorporating the concepts disclosed herein may be utilized with a variety of products.
General Footwear Structure
An article of footwear 10 is depicted in
Upper 20 is depicted as having a substantially conventional configuration incorporating a plurality material elements (e.g., textile, foam, leather, and synthetic leather) that are stitched or adhesively bonded together to form an interior void for securely and comfortably receiving a foot. The material elements may be selected and located with respect to upper 20 in order to selectively impart properties of durability, air-permeability, wear-resistance, flexibility, and comfort, for example. An ankle opening 21 in heel region 13 provides access to the interior void. In addition, upper 20 may include a lace 22 that is utilized in a conventional manner to modify the dimensions of the interior void, thereby securing the foot within the interior void and facilitating entry and removal of the foot from the interior void. Lace 22 may extend through apertures in upper 20, and a tongue portion of upper 20 may extend between the interior void and lace 22. Given that various aspects of the present application primarily relate to sole structure 30, upper 20 may exhibit the general configuration discussed above or the general configuration of practically any other conventional or non-conventional upper. Accordingly, the overall structure of upper 20 may vary significantly.
Sole structure 30 is secured to upper 20 and has a configuration that extends between upper 20 and the ground. In effect, therefore, sole structure 30 is located to extend between the foot and the ground. In addition to attenuating ground reaction forces (i.e., providing cushioning for the foot), sole structure 30 may provide traction, impart stability, and limit various foot motions, such as pronation. The primary elements of sole structure 30 are a midsole 31 and an outsole 32. Midsole 31 may be formed from a polymer foam material, such as polyurethane or ethylvinylacetate, that encapsulates a fluid-filled chamber 33. In addition to the polymer foam material and chamber 33, midsole 31 may incorporate one or more additional footwear elements that enhance the comfort, performance, or ground reaction force attenuation properties of footwear 10, including plates, moderators, lasting elements, or motion control members. Outsole 32, which may be absent in some configurations of footwear 10, is secured to a lower surface of midsole 31 and may be formed from a rubber material that provides a durable and wear-resistant surface for engaging the ground. In addition, outsole 32 may also be textured to enhance the traction (i.e., friction) properties between footwear 10 and the ground. Sole structure 30 may also incorporate an insole or sockliner that is located with in the void in upper 20 and adjacent a plantar (i.e., lower) surface of the foot to enhance the comfort of footwear 10.
Chamber Configuration
Chamber 33 is depicted individually in
The primary elements of chamber 33 are a barrier 40 and a tensile member 50. Barrier 40 forms an exterior of chamber 33 and (a) defines an interior void that receives both a pressurized fluid and tensile member 50 and (b) provides a durable sealed barrier for retaining the pressurized fluid within chamber 33. The polymer material of barrier 40 includes an upper barrier portion 41, an opposite lower barrier portion 42, and a sidewall barrier portion 43 that extends around a periphery of chamber 33 and between barrier portions 41 and 42. Tensile member 50 is located within the interior void and has a configuration of a spacer-knit textile that includes an upper tensile layer 51, an opposite lower tensile layer 52, and a plurality of connecting members 53 that extend between tensile layers 51 and 52. Whereas upper tensile layer 51 is secured to an inner surface of upper barrier portion 41, lower tensile layer 52 is secured to an inner surface of lower barrier portion 42. Either adhesive bonding or thermobonding, for example, may be utilized to secure tensile member 50 to barrier 40.
In manufacturing chamber 33, a pair of polymer sheets may be molded and bonded during a thermoforming process to define barrier portions 41-43. More particularly, the thermoforming process (a) imparts shape to one of the polymer sheets in order to form upper barrier portion 41 and an upper area of sidewall portion 43 (b) imparts shape to the other of the polymer sheets in order to form lower barrier portion 42 and a lower area of sidewall barrier portion 43, and (c) forms a peripheral bond 44 that joins a periphery of the polymer sheets and extends around sidewall barrier portion 43. The thermoforming process may also locate tensile member 50 within chamber 33 and bond tensile member 50 to each of barrier portions 41 and 42. Although substantially all of the thermoforming process may be performed with a mold, as described in greater detail below, each of the various parts of the process may be performed separately in forming chamber 33.
Following the thermoforming process, a fluid may be injected into the interior void and pressurized. The pressurized fluid exerts an outward force upon chamber 33, which tends to separate barrier portions 41 and 42. Tensile member 50, however, is secured to each of barrier portions 41 and 42 in order to retain the intended shape of chamber 33 when pressurized. More particularly, connecting members 53 extend across the interior void and are placed in tension by the outward force of the pressurized fluid upon barrier 40, thereby preventing barrier 40 from expanding outward and retaining the intended shape of chamber 33. Whereas peripheral bond 44 joins the polymer sheets to form a seal that prevents the fluid from escaping, tensile member 50 prevents chamber 33 from expanding outward or otherwise distending due to the pressure of the fluid. That is, tensile member 50 effectively limits the expansion of chamber 33 to retain an intended shape of surfaces of barrier portions 41 and 42.
Chamber 33 is shaped and contoured to provide a structure that is suitable for footwear applications. As noted above, chamber 33 has a shape that fits within a perimeter of midsole 31 and extends under substantially all of the foot, thereby corresponding with a general outline of the foot. In addition, surfaces corresponding with barrier portions 41 and 42 are contoured in a manner that is suitable for footwear applications. With reference to
The fluid within chamber 33 may be pressurized between zero and three-hundred-fifty kilopascals (i.e., approximately fifty-one pounds per square inch) or more. In addition to air and nitrogen, the fluid may include octafluorapropane or be any of the gasses disclosed in U.S. Pat. No. 4,340,626 to Rudy, such as hexafluoroethane and sulfur hexafluoride. In some configurations, chamber 33 may incorporate a valve or other structure that permits the individual to adjust the pressure of the fluid.
A wide range of polymer materials may be utilized for chamber 33. In selecting materials for barrier 40, engineering properties of the material (e.g., tensile strength, stretch properties, fatigue characteristics, dynamic modulus, and loss tangent) as well as the ability of the material to prevent the diffusion of the fluid contained by barrier 40 may be considered. When formed of thermoplastic urethane, for example, barrier 40 may have a thickness of approximately 1.0 millimeter, but the thickness may range from 0.25 to 2.0 millimeters or more, for example. In addition to thermoplastic urethane, examples of polymer materials that may be suitable for chamber 33 include polyurethane, polyester, polyester polyurethane, and polyether polyurethane. Barrier 40 may also be formed from a material that includes alternating layers of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer, as disclosed in U.S. Pat. Nos. 5,713,141 and 5,952,065 to Mitchell, et al. A variation upon this material may also be utilized, wherein a center layer is formed of ethylene-vinyl alcohol copolymer, layers adjacent to the center layer are formed of thermoplastic polyurethane, and outer layers are formed of a regrind material of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer. Another suitable material for barrier 40 is a flexible microlayer membrane that includes alternating layers of a gas barrier material and an elastomeric material, as disclosed in U.S. Pat. Nos. 6,082,025 and 6,127,026 to Bonk, et al. Additional suitable materials are disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy. Further suitable materials include thermoplastic films containing a crystalline material, as disclosed in U.S. Pat. Nos. 4,936,029 and 5,042,176 to Rudy, and polyurethane including a polyester polyol, as disclosed in U.S. Pat. Nos. 6,013,340; 6,203,868; and 6,321,465 to Bonk, et al.
In order to facilitate bonding between tensile member 50 and barrier 40, polymer supplemental layers may be applied to each of tensile layers 51 and 52. When heated, the supplemental layers soften, melt, or otherwise begin to change state so that contact with barrier portions 41 and 42 induces material from each of barrier 40 and the supplemental layers to intermingle or otherwise join with each other. Upon cooling, therefore, the supplemental layer is permanently joined with barrier 40, thereby joining tensile member 50 with barrier 40. In some configurations, thermoplastic threads or strips may be present within tensile layers 51 and 52 to facilitate bonding with barrier 40, as disclosed in U.S. Pat. No. 7,070,845 to Thomas, et al., or an adhesive may be utilized to secure barrier 40 and tensile member 50.
Tensile Member Configuration
Tensile member 50, which is depicted individually in
The lengths of connecting members 53 vary throughout tensile member 50. As with chamber 33, tensile member 50 has a tapered configuration between heel region 13 and forefoot region 11. In order to impart the tapered configuration, the lengths of connecting members 53 may decrease between heel region 13 and forefoot region 11. As with chamber 33, tensile member 50 also forms a depression in heel region 13. In order to provide the depression, connecting members 53 located adjacent to sides 14 and 15 may be longer than in a center of heel region 13. Accordingly, by varying the lengths of connecting members 53, contours may be imparted to tensile member 50.
Tensile member 50 is formed as a unitary (i.e., one-piece) textile element having the configuration of a spacer-knit textile. A variety of knitting techniques may be utilized to form tensile member 50 and impart a specific configuration (e.g., taper, contour, length, width, thickness) to tensile member 50. In general, knitting involves forming courses and wales of intermeshed loops of a yarn or multiple yarns. In production, knitting machines may be programmed to mechanically-manipulate yarns into the configuration of tensile member 50. That is, tensile member 50 may be formed by mechanically-manipulating yarns to form a one-piece textile element that has a particular configuration. The two major categories of knitting techniques are weft-knitting and warp-knitting. Whereas a weft-knit fabric utilizes a single yarn within each course, a warp-knit fabric utilizes a different yarn for every stitch in a course.
Although tensile member 50 may be formed through a variety of different knitting processes, an advantage of flat-knitting, which is a specific type of weft-knitting, is that generally three-dimensional structures may be produced. In contrast with the “flat” terminology in “flat-knitting”, therefore, non-planar, curved, or otherwise generally three-dimensional structures may be produced through flat-knitting. As discussed above, tensile member 50 is a one-piece, spacer-knit textile element that includes upper tensile layer 51, lower tensile layer 52, and connecting members 53, which may be formed through flat-knitting. In general, flat-knitting is a method for producing a knitted fabric in which the fabric is turned periodically (i.e., the fabric is knitted from alternating sides). The two sides (otherwise referred to as faces) of the fabric are conventionally designated as the right side (i.e., the side that faces outwards, towards the viewer) and the wrong side (i.e., the side that faces inwards, away from the viewer). Although flat-knitting provides a suitable manner for forming restriction structure 30, other types of knitting may also be utilized, including wide tube circular knitting, narrow tube circular knit jacquard, single knit circular knit jacquard, double knit circular knit jacquard, warp knit jacquard, and double needle bar raschel knitting, for example. Accordingly, various weft-knitting and warp-knitting techniques may be utilized to manufacture tensile member 50.
Although one or more yarns may be mechanically-manipulated by an individual to form tensile member 50 (i.e., tensile member 50 may be formed by hand), flat-knitting machines may provide an efficient manner of forming relatively large numbers of tensile member 50. The flat-knitting machines may also be utilized to vary the dimensions of tensile member 50 to form tensile members 50 that are suitable for individuals with differently-sized feet. Additionally, the flat-knitting machines may be utilized to vary the configuration of tensile member 50 to form tensile members 50 that are suitable for both left and right feet. Accordingly, the use of mechanical flat-knitting machines may provide an efficient manner of forming multiple tensile members 50 having different sizes and configurations. Examples of flat-knitting machines that may be utilized to produce various sizes and configurations of tensile members 50 include.
Whereas edges of many textile materials are cut to expose ends of the yarns forming the textile materials, tensile member 50 may be formed to have a finished configuration. That is, flat-knitting or other knitting techniques may be utilized to form tensile member 50 such that ends of the yarns within tensile member 50 are substantially absent from the edges of tensile layers 51 and 52. An advantage of the finished configuration formed through flat-knitting is that the yarns forming the edges of tensile layers 51 and 52 are less likely to unravel, thereby degrading the structure of tensile member 50. In addition, loose yarns are also less likely to inhibit the aesthetic appearance of the interior of chamber 33 In other words, the finished configuration of tensile member 50 may enhance the durability and aesthetic qualities of chamber 33.
For purposes of the present discussion, the term “yarn” or variants thereof is intended to encompass a variety of generally one-dimensional materials (e.g., filaments, fibers, threads, strings, strands, and combinations thereof) that may be utilized to form a textile. The properties of tensile member 50 may relate to the specific materials that are utilized in the yarns. Examples of properties that may be relevant in selecting specific yarns for tensile member 50 include tensile strength, tensile modulus, density, flexibility, tenacity, resistance to abrasion, and resistance to degradation (e.g., from water, light, and chemicals). Examples of suitable materials for the yarns include rayon, nylon, polyester, polyacrylic, silk, cotton, carbon, glass, aramids (e.g., para-aramid fibers and meta-aramid fibers), ultra high molecular weight polyethylene, and liquid crystal polymer. Although each of these materials exhibit properties that are suitable for tensile member 50, each of these materials exhibit different combinations of material properties. Accordingly, the properties of yarns formed from each of these materials may be compared in selecting materials for the yarns within tensile member 50. Moreover, factors relating to the combination of yarns and the type of knit or type of textile may be considered in selecting a configuration for tensile member 50.
A further advantage of flat-knitting or other manufacturing techniques for tensile member 50 relates to the placement of yarns and course density. The type of yarn utilized in different areas of tensile member 50 may change to vary the properties of the different areas. For example, one area of tensile member 50 may stretch more than another area. Similarly, the type of yarn utilized on different sides of tensile member 50 may change to vary the properties of the different sides. Different properties may also be gained by changing the course density in different areas or on different sides of tensile member 50.
Based upon the above discussion, tensile member 50 incorporates various advantages, including contouring and the finished configuration. The contouring of tensile member 50 may be utilized to impart a variety of shapes to surfaces of chamber 33. As discussed above, chamber 33 is tapered between heel region 13 and forefoot region 11, and chamber 33 has a depression in heel region 13. These contours are imparted to chamber 33 by the configuration of tensile member 50. A variety of other contours (i.e., tapers, depressions, protrusions) may be imparted to chamber 33 by modifying the configuration of tensile member 50. In addition, the finished configuration of tensile member 50 may be utilized to enhance the durability and aesthetic qualities of chamber 33. Whereas the tensile members of some prior chambers were cut from a larger textile element, thereby exposing ends of the yarns, the knitting technique (e.g., with a flat-knitting machine) utilized to manufacture tensile member 50 may form tensile member 50 as an individual component with a finished configuration. In effect, tensile member 50 may be knitted with a flat-knitting machine to have the general shape of chamber 33. That is, tensile member 50 may be formed as depicted in
Manufacturing Process
Although a variety of manufacturing processes may be utilized to form chamber 33, an example of a suitable thermoforming process will now be discussed. With reference to
In manufacturing chamber 33, one or more of an upper polymer layer 71, a lower polymer layer 72, and tensile member 50 are heated to a temperature that facilitates bonding between the components. Depending upon the specific materials utilized for tensile member 50 and polymer layers 71 and 72, which form barrier 40, suitable temperatures may range from 120 to 200 degrees Celsius (248 to 392 degrees Fahrenheit) or more. As an example, a material having alternating layers of thermoplastic polyurethane and ethylene-vinyl alcohol copolymer may be heated to a temperature in a range of 149 to 188 degrees Celsius (300 and 370 degrees Fahrenheit) to facilitate bonding. Various radiant heaters or other devices may be utilized to heat the components of chamber 33. In some manufacturing processes, mold 60 may be heated such that contact between mold 60 and the components of chamber 33 raises the temperature of the components to a level that facilitates bonding.
Following heating, the components of chamber 33 are located between mold portions 61 and 62, as depicted in
At the stage depicted in
In order to provide a second means for drawing polymer layers 71 and 72 into contact with the various contours of mold 60, the area between polymer layers 71 and 72 and proximal tensile member 50 may be pressurized. During a preparatory stage of this method, an injection needle may be located between polymer layers 71 and 72, and the injection needle may be located such that ridges 63 and 64 envelop the injection needle when mold 60 closes. A gas may then be ejected from the injection needle such that polymer layers 71 and 72 engage ridges 63 and 64, thereby forming an inflation conduit 73 (see
As mold 60 closes further, ridges 63 and 64 bond upper polymer layer 71 to lower polymer layer 72, as depicted in
When bonding is complete, mold 60 is opened and chamber 33 and excess portions of polymer layers 71 and 72 are removed and permitted to cool, as depicted in
Based upon the above discussion, mold 60 is utilized to (a) impart shape to upper polymer layer 71 in order to form upper barrier portion 41 and an upper area of sidewall portion 43 (b) impart shape to lower polymer layer 72 in order to form lower barrier portion 42 and a lower area of sidewall barrier portion 43, and (c) forms peripheral bond 44 between polymer layers 71 and 72. Mold 60 also (a) bonds upper tensile layer 51 to the portion of upper polymer layer 71 that forms upper barrier portion 41 and (b) bonds lower tensile layer 52 to the portion of lower polymer layer 72 that forms lower barrier portion 42.
The surfaces of mold 60 that shape barrier portions 41 and 42 are depicted as being substantially parallel and planar. Chamber 33, however, exhibits a tapered configuration between heel region 13 and forefoot region 11, and upper barrier portion 41 forms a depression in heel region 13. When chamber 33 is pressurized, these contours may arise due to the configuration of tensile member 50. In further manufacturing processes, however, mold 60 may incorporate features (e.g., contours, protrusions, shaping) that correspond with the tapering and depression to facilitate the formation of the tapering and the depression. In addition to the configuration of tensile member 50, the configuration of mold 60 may also be utilized to impart a specific shape to chamber 33.
Further Configurations
A suitable configuration for a fluid-filled chamber 33 that may be utilized with footwear 10 is depicted in
Chamber 33 is discussed above as being tapered between heel region 13 and forefoot region 11. As depicted in
Although chamber 33 forms a depression in heel region 13, sides 14 and 15 have substantially identical thicknesses. In some configurations, chamber 33 may taper between medial side 15 and lateral side 14, as depicted in
Peripheral bond 44 is depicted as being located between upper barrier portion 41 and lower barrier portion 42. That is, peripheral bond 44 is centered between barrier portions 41 and 42. In other configurations, however, peripheral bond 44 may be located on the same plane as either of barrier portions 41 and 42. As an example, peripheral bond 44 is depicted as being level with upper barrier portion 41 in
Chamber 33 is discussed above as having a configuration that is suitable for footwear. In addition to footwear, chambers having similar configurations may be incorporated into other types of apparel and athletic equipment, including helmets, gloves, and protective padding for sports such as football and hockey. Similar chambers may also be incorporated into cushions and other compressible structures utilized in household goods and industrial products. Referring to
The invention is disclosed above and in the accompanying figures with reference to a variety of configurations. The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the configurations described above without departing from the scope of the present invention, as defined by the appended claims.
