Patent Publication Number: US-2011067263-A1

Title: Article of Footwear Having Midsole with Support Pillars and Method of Manufacturing Same

Description:
RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 12/632,305, filed Dec. 7, 2009, which is a divisional of application Ser. No. 12/138,744, filed Jun. 13, 2008, now U.S. Pat. No. 7,644,462, issued Jan. 12, 2010, which is a divisional of application Ser. No. 11/206,254, filed on Aug. 17, 2005, now U.S. Pat. No. 7,401,418, issued Jul. 22, 2008, each of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to an article of footwear, and, in particular, to an article of footwear having a midsole with support pillars positioned therein and a method of manufacturing the same. 
     BACKGROUND OF THE INVENTION 
     A conventional article of athletic footwear includes two primary elements, an upper and a 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 fraction 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 fraction. The midsole is the primary sole structure element that imparts cushioning and controls foot motions. Suitable polymer foam materials for the midsole include ethylvinylacetate or polyurethane that compress resiliently under an applied load to attenuate ground reaction forces. Conventional polymer foam materials are resiliently compressible, in part, due to the inclusion of a plurality of open or closed cells that define an inner volume substantially displaced by gas. The polymer foam materials of the midsole may also absorb energy when compressed during ambulatory activities. 
     It would be desirable 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 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 embodiments. 
     SUMMARY 
     The principles of the invention may be used to advantage to provide an article of footwear with support pillars. In accordance with a first aspect, an article of footwear includes an upper, a sole assembly, and a support assembly positioned in the sole assembly and including a plurality of pillars. Each pillar includes an outer layer and an inner layer of cushioning material contained with the outer layer. 
     In accordance with another aspect, an article of footwear includes an upper, a sole assembly, and a support assembly positioned in a heel portion of the sole assembly and including a plurality of pillars. Each pillar includes an outer layer having an upper portion including a first recess formed of walls and a bottom. A lower portion has a second recess formed of walls and a top, with the bottom of the first recess and the top of the second recess being in abutting relationship. An aperture extends through the bottom of the first recess and the top of the second recess. An inner layer of cushioning material is contained with the outer layer and extends through the aperture. 
     In accordance with a further aspect, a method of manufacturing an article of footwear includes the steps of forming a fluid-filled bag having a plurality of apertures extending therethrough with a first mold; inserting the fluid-filled bag into a second mold; pouring a cushioning material into the second mold to form a support assembly with cushioning material covering the bag and extending through the apertures of the fluid-filled bag to form pillars; removing the support assembly from the second mold; cutting away a portion of the cushioning material about a periphery of the support assembly; cutting away a portion of a periphery of the fluid-filled bag to expose the pillars formed therein; and securing the support assembly between an upper and an outsole to form an article of footwear. 
     In accordance with yet another aspect, an article of footwear formed by the steps of forming a fluid-filled bag in a first mold and including a plurality of first recesses on a first side thereof and having a bottom, a plurality of second recesses on a second side thereof and having a top with a plurality of apertures extending therethrough, with each aperture extending through the bottom of a first recess and a top of a second recess; inserting the fluid-filled bag into a second mold; pouring a cushioning material into the second mold to form a support assembly with cushioning material covering the bag and extending into the recesses and through the apertures of the fluid-filled bag to form pillars; removing the support assembly from the second mold; cutting away a portion of the cushioning material about a periphery of the support assembly; cutting away a portion of a periphery of the fluid-filled bag to expose the pillars formed therein; and securing the support assembly between an upper and an outsole to form an article of footwear. 
     Substantial advantage is achieved by providing an article of footwear with support pillars. In particular, certain embodiments of the article of footwear with support pillars can provide increased support, comfort and performance. 
     These and additional features and advantages disclosed here will be further understood from the following detailed disclosure of certain embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of an article of footwear. 
         FIG. 2  is a perspective view of a mold used to form a fluid-filled bag used in the formation of a support assembly of the article of footwear of  FIG. 1 . 
         FIGS. 3A-C  are elevation views of the use of the mold of  FIG. 2  to form the fluid-filled bag used in the formation of the support assembly of the article of footwear of  FIG. 1 . 
         FIG. 4  is a perspective view of the fluid-filled bag formed in the mold of  FIG. 2 . 
         FIG. 5  is a perspective view of a mold used to form the support assembly of the article of footwear of  FIG. 1 . 
         FIG. 6  is a perspective view of the support assembly formed in the mold of  FIG. 5 , shown being trimmed to its final form. 
         FIG. 7  is a perspective view of the support assembly formed in the mold of  FIG. 5 , shown in its final form. 
         FIG. 8  is a section view of a portion of a pillar of the support assembly of  FIG. 7 . 
         FIG. 9  is a section view of a portion of a pillar of another embodiment of the support assembly of  FIG. 7 . 
         FIG. 10  is a perspective view of another embodiment of the fluid-filled bag formed in the mold of  FIG. 2 . 
     
    
    
     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. 
     DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS 
     The present invention may be embodied in various forms. A preferred embodiment of an article of footwear  10  is shown in  FIG. 1 . Footwear  10  includes an upper  12  and a sole assembly  14  secured to upper  12 . Sole assembly  14  may be secured to upper  12  by adhesive or any other suitable means. Footwear  10  has a medial, or inner, side  13  and a lateral, or outer, side  15 . For purposes of general reference, footwear  10  may be divided into three general portions: a forefoot portion  16 , a midfoot portion  18 , and a heel portion  20 . Portions  16 ,  18 , and  20  are not intended to demarcate precise areas of footwear  10 . Rather, portions  16 ,  18 , and  20  are intended to represent general areas of footwear  10  that provide a frame of reference during the following discussion. 
     Unless otherwise stated, or otherwise clear from the context below, directional terms used herein, such as rearwardly, forwardly, top, bottom, inwardly, downwardly, upwardly, etc., refer to directions relative to footwear  10  itself. Footwear  10  is shown in  FIG. 1  to be disposed substantially horizontally, as it would be positioned on a horizontal surface when worn by a wearer. However, it is to be appreciated that footwear  10  need not be limited to such an orientation. Thus, in the illustrated embodiment of  FIG. 1 , rearwardly is toward heel portion  20 , that is, to the left as seen in  FIG. 1 . Naturally, forwardly is toward forefoot portion  16 , that is, to the right as seen in  FIG. 1 , and downwardly is toward the bottom of the page as seen in  FIG. 1 . Top refers to elements toward the top of the page as seen in  FIG. 1 , while bottom refers to elements toward the bottom of the page as seen in  FIG. 1 . Inwardly is toward the center of footwear  10 , and outwardly is toward the outer peripheral edge of footwear  10 . 
     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 attached to 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. Suitable materials for midsole  22  include polymer foam materials such as ethylvinylacetate or polyurethane, or any other material that compresses resiliently. Outsole  24  is attached to the lower surface of midsole  22  by adhesive or other suitable means. Suitable materials for outsole  24  include polymers, e.g., polyether-block co-polyamide polymers (sold as Pebax® by ATOFINA Chemicals of Philadelphia, Pa.), and nylon resins such as Zyte®, sold by Dupont. 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 may comprise a bottom surface of midsole  22  that provides the external traction surface of sole assembly  14 . 
     Sole assembly  14  includes a support assembly  26 , which includes a plurality of pillars  25 , described in greater detail below. As shown in the embodiments illustrated herein, support assembly  26  is positioned in heel portion  20  of footwear  10 . It is to be appreciated that support assembly  26  can be positioned in one or more of heel portion  20 , midfoot portion  18  and/or forefoot portion  16 . As illustrated here, support assembly  26  is configured to span across footwear  10 . However, it is to be appreciated that support assembly  26  could be configured to be positioned only on lateral side  15  or only on medial side  13  of footwear  10 . In other embodiments, support assembly  26  could have one portion extending across footwear  10  with another portion positioned in only lateral side  15  or medial side  13 . Other configurations of support assembly  26  will become readily apparent to those skilled in the art, given the benefit of this disclosure. 
     The formation of a fluid-filled bag  27  (seen in  FIG. 4 ) for use in forming support assembly  26  is shown in  FIGS. 2-4 . A first mold  30 , used to form fluid-filled bag  27  is seen in  FIG. 2 . First mold  30  includes a first portion  32  having a first recess  34  formed therein. A plurality of first projections  36  extend outwardly from the bottom  38  of first recess  34 . A post  40  extends outwardly from each first projection  36 . A first channel  41  extends between first recess  34  and an exterior of first portion  32 . 
     A second portion  42  of first mold  30  is joined to first portion  32  by a hinge  43  and includes a second recess  44  formed therein. A plurality of second projections  46  extend outwardly from a bottom  48  of second recess  44 . Each second projection  46  includes an aperture  50  that receives a corresponding post  40  of first portion  32  when first mold  30  is closed. A second channel  51  extends between second recess  44  and an exterior of second portion  42 . Second channel  51  mates with first channel  41  of first portion  32  when first mold  30  is closed, providing an input port, as described in greater detail below. First projections  36  and second projections  46  combine to define first and second recesses  66 ,  72 , respectively, of fluid-filled bag  27 , as described in greater detail below. 
     First mold  30  is used to form fluid-filled bag  27  as seen in  FIGS. 3A-C . An injector  52  outputs a substantially tubular sheet of material  54  downwardly in the direction of Arrow A from an aperture  56  formed therein. First mold  30  is then closed about sheet of material  54 . A needle  58  is then inserted into an input port  53  (formed by the mating of first channel  41  and second channel  51  of first mold  30 ) in the direction of Arrow B and injects a fluid, such as air, into first mold  30 , forcing material  54  against the inner surfaces of first mold  30  to form fluid-filled bag  27  (seen in  FIG. 4 ). In certain embodiments, a vacuum may be applied to the exterior of sheet of material  54  within first mold  30 . 
     Material  54  used to form fluid-filled bag  27  may be thermoplastic polyurethane (TPU), polyurethane, polyester, polyester polyurethane, polyether polyurethane, ethyl vinyl alcohol copolymers (EVOH) or scrap material. Other suitable materials for use in forming fluid-filled bag  27  will become readily apparent to those skilled in the art, given the benefit of this disclosure. 
     As seen in  FIG. 4 , fluid-filled bag  27  is formed of an upper portion  60  and a lower portion  62  joined by a parting line  64  created during the molding process by the junction of first portion  32  and second portion  42  of first mold  30 . Upper portion  60  includes a plurality of first recesses  66  having one or more walls  68  and a bottom  70 . Walls  68  of first recesses  66  may taper inwardly toward bottom  70 . First recesses  66  are formed by first projections  36  of first portion  32  of first mold  30 . 
     Lower portion  62  similarly has a plurality of second recesses  72  having one or more walls  74  and a top  76 , which is in abutting relationship with bottom  70  of a corresponding first recess  66 . Walls  74  of second recesses  72  may taper inwardly toward top  76 . Second recesses  72  are formed by second projections  46  of second portion  42  of first mold  30 . During the molding process described above with respect to  FIGS. 3A-C , a bottom  70  of a first recess  66  and a top  76  of a corresponding second recess  72  are sealed with one another as first projections  36  and second projections  46  sandwich sheet of material  54  therebetween. An aperture  78  may extend through bottom  70  of a first recess  66  and the corresponding top  76  of a second recess  72 . Apertures  78  are formed by projections  40  of first portion  32  of first mold  30 . 
     In the embodiment illustrated, each first and second recess  66 ,  72  has a substantially triangular shape and, therefore, includes three walls  68 ,  74 , respectively. Consequently, first and second projections  36 ,  46  have substantially triangular shapes as well. It is to be appreciated that other shapes for first and second recesses  66 ,  72  are considered to be within the scope of the present invention, and that the number and configuration of the walls for first and second recesses  66 ,  72  will vary accordingly. Thus, for example, first and second recesses  66 ,  72  may have square or rectangular shapes, which would require four walls  68 ,  74 , respectively. In such an embodiment, first and second projections  36 ,  46  of first mold  30  will naturally have corresponding square or rectangular shapes. Other shapes and configurations for first and second recesses  66 ,  72  and, naturally, first and second projections  36 ,  46  will become readily apparent to those skilled in the art, given the benefit of this disclosure. 
     In other embodiments, fluid-filled bag  27  may be produced by the well known thermoforming process, in which a pair of polymer layers are heated and placed between a pair of mold portions. A vacuum on the exterior of the layers and/or pressure between the layers draws the layers into contours of the mold. The peripheries of the layers are then pressed together to form a peripheral bond, and various interior locations may also be pressed together to form interior bonds, thereby forming fluid-filled bag  27 . 
     In other embodiments, fluid-filled bag  27  may be manufactured by a two-film technique, often referred to as twin-sheet bonding, wherein two separate layers of elastomeric film are formed to have the overall shape of the bag. The layers are then welded together along their respective peripheries to form an upper surface, a lower surface, and sidewalls of the bag, and the layers are welded together at predetermined interior locations to impart a desired configuration to the bag. That is, interior portions of the layers are connected to form chambers of a predetermined shape and size at desired locations. The bag is then subsequently pressurized above ambient pressure by inserting a nozzle or needle, which is connected to a fluid pressure source, into a fill inlet formed in the bag. After the bag is pressurized, the nozzle is removed and the fill inlet is sealed, by welding for example. 
     In other embodiments, fluid-filled bag  27  may be produced by the well known blowmolding process, in which a liquefied elastomeric material is placed in a mold having the desired overall shape and configuration of fluid-filled bag  27 . Pressurized air is provided through an opening formed in the mold. The pressurized air forces the liquefied elastomeric material against the inner surfaces of the mold and causes the material to harden in the mold, thereby forming the fluid-filled bag  27  having the desired configuration. 
     In certain embodiments, fluid-filled bag  27  may be colored to provide a desired aesthetic appearance. Fluid-filled bag  27  may be painted after it has been formed in first mold  30 , e.g., spray painted. The desired color may be added by screen printing, sublimation or any other desired method. In other embodiments, pigment may be added to material  54 , which is used to form fluid-filled bag  27 , in order to provide a desired color. Other methods of imparting color to fluid-filled bag  27  will become readily apparent to those skilled in the art, given the benefit of this disclosure. It is to be appreciated that fluid-filled bag  27  may be painted a single color, or any combination of desired colors, and in any desired pattern to produce a desired aesthetic appearance. 
     A second mold  80 , seen in  FIG. 5 , is used with fluid-filled bag  27  to form support assembly  26 . Second mold  80  has a first portion  82  having a recess  84  formed therein. A first channel  86  extends from a periphery of first portion  82  to recess  84 . A second portion  88  has a projection  90  formed thereon, with a second channel  92  extending from a periphery of second portion  88  to projection  90 . First portion  82  has a plurality of pins  94  that are received in corresponding apertures  96  formed in second portion  88  in order to register and align first portion  82  with second portion  88 . 
     Fluid-filled bag  27  is placed in recess  84  of first portion  82 . A cushioning material  98 , seen in  FIGS. 6-8 , is then poured into recess  84 , covering fluid-filled bag  27 . Cushioning material  98  covers the exterior of fluid-filled bag  27 , as well as filling first and second recesses  66 ,  72  and extending through apertures  78 , thereby forming pillars  25 , seen in  FIGS. 6-8 . Second portion  88  is then placed on first portion  82  such that first and second channels  86 ,  92  are aligned with one another to define a channel that receives needle  58  used to form fluid-filled bag  27 , a portion of projection  90  is received in recess  84 , and cushioning material  98  expands and fills first and second recesses  66 ,  72  and recess  84 . Pillars  25  may have visible a parting line  102 , formed at the junction of walls  68  and  74  of first recess  66  and second recess  72 , respectively, during the molding process. 
     A strip  104  of cushioning material  98  about the periphery of support assembly  26  and the periphery  106  of fluid-filled bag  27  is then cut away, exposing support assembly  26 , as seen in  FIGS. 6-7 . Pillars  25  of support assembly  26  can be seen to extend between the cushioning material  98  that extends over the upper portion  60  of fluid-filled bag  27  and the cushioning material  98  that extends beneath the lower portion  62  of fluid-filled bag  27 . Pillars  25 , as seen in  FIG. 8 , are formed of an outer layer  108 , which comprises walls  68 ,  74  of first and second recesses  66 ,  72 , respectively of fluid-filled bag  27 , and an inner layer  110  of cushioning material  98 . Cushioning material  98  and, naturally, pillars  25 , serve to act as a portion of midsole  22  of footwear  10 . 
     In certain embodiments, cushioning material  98  is poured polyurethane. It is to be appreciated that other materials that will enhance the cushioning effect of support assembly  26  can be used for cushioning material  98 , such as ethyl vinyl acetate (EVA). Other suitable materials for cushioning material  98  will become readily apparent to those skilled in the art, given the benefit of this disclosure. In certain embodiments, cushioning material  98  could be pre-formed and merely inserted into first and second recesses  66 ,  72  and around fluid-filled bag  27 . 
     As seen in  FIG. 8 , pillars  25  may taper inwardly from their top toward a midpoint thereof, at parting line  102 , and inwardly from a bottom thereof to the midpoint at parting line  102 . 
     It is to be appreciated that cushioning material  98  may also be colored, and that different portions of cushioning material  98  may have different colors, thereby allowing one or more pillars  25  to have a first color with one or more other pillars  25  having a second different color. It is to be appreciated that any number of different colors can be used on pillars  25 . Certain portions of pillars  25  may have one color with other portions having different colors. Thus, outer layer  108  and inner layer  110  of pillars  25  can have any desired color combination to provide a desired aesthetic design. 
     In addition, cushioning material  98  may not be uniform throughout support assembly  26 , that is, a first cushioning material  98  having a first set of characteristics (density, compressibility, stiffness, etc.) could be initially poured into a first portion of second mold  80  and a second cushioning material  98  that is different than the first (that is, it has a set of characteristics different than that of the first cushioning material) could be poured into a second portion of second mold  80 . It is to be appreciated that any number of different cushioning materials can be provided throughout support assembly  26 . 
     In another embodiment, as seen in  FIG. 9 , inserts  112  may be positioned within fluid-filled bag  27 . As seen in this embodiment, inserts  112  are positioned in first and second recesses  66 ,  72  and include a central aperture  114  extending therethrough. Cushioning material  98  passes through apertures  114  and fills the interior of inserts  112 , such that inserts  112  are positioned within cushioning material  98  or inner layer  110 . Inserts  112  act to provide additional support for pillars  25 . In certain embodiments, inserts  112  may be formed of a material having a greater stiffness or rigidity than that of cushioning material  98 . For example, inserts  112  may be formed of plastic. 
     It is to be appreciated that in certain embodiments, outer layer  108  could be formed by injection molding material into a desired shape. In such an embodiment, the injection molded material is then placed into second mold  80  and cushioning material  98  is poured into the mold, forming pillars  25 . 
     It is to be appreciated that in certain embodiments, as depicted in  FIG. 10 , fluid-filled bag  27  may have first recesses  66  formed on only one side thereof, with the other side of fluid-filled bag  27  being substantially flat. Thus, cushioning material  98  extends into each first recess  66  such that the walls  68  of first recess  66  and cushioning material  98  form outer layer  108  and inner layer  110 , respectively, of pillars  25 . 
     It is to be appreciated that in certain embodiments, as seen in  FIG. 10 , fluid-filled bag  27  may include interior walls or partitions  114  defining chambers  116 . In such embodiments, only a portion of periphery  106  of fluid-filled bag  27  may be cut away in the manner described above, thereby leaving intact some chambers  116  of fluid-filled bag  27 . Chambers  116  may be at ambient pressure or inflated to a higher pressure. Chambers  116  can provide additional support for support assembly  26 . 
     By providing particular shapes, and sizes and locations of first and second recesses  66 ,  72 , the support provided by pillars  25  can be optimized. That is, the performance characteristics of footwear  10  can be altered by positioning pillars  25  in desired locations and by forming pillars  25  with desired shapes. Accordingly, footwear  10  can be optimized for particular activities, particular foot shapes or for any other reason. Similarly, the amount and type of cushioning material  98  can be varied throughout footwear  10  to optimize performance. 
     Similarly, by varying the thickness of the walls of fluid-filled bag  27 , the thickness of outer layers  108  can be varied, thereby modifying the performance of pillars  25 . 
     In light of the foregoing disclosure of the invention and description of various 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.