Footwear with dual-density midsole and deceleration zones

Abstract

An athletic shoe midsole includes a hard elastic stabilizing member that extends generally around a central opening through which a relatively soft elastic cushioning layer extends downwardly from a heel center beneath a wearer's calcaneus bone to thereby form a heel-cushioning pillar. The stabilizing member extends along lateral and medial sides of the pillar to prevent pronation and supination, and preferably includes a protrusion that extends into a depression in the heel-cushioning pillar in alignment with a line of flexure of the heel region to thereby affect flexure characteristics of a heel region of the shoe. The midsole may also include flex grooves, channels, and/or notches aligned with the line of flexure for promoting the desired flexure characteristics in the heel region of the sole and for helping decelerate the wearer's heel-toe gait during the stance phase of the wearer's gait cycle.

1 . In an athletic shoe having a shoe upper and a sole, the sole including a heel region having lateral and medial side margins, and the sole including an outsole and a midsole interposed between the outsole and the shoe upper, an improved sole, comprising: 
 a soft elastic cushioning layer extending under the shoe upper, the cushioning layer including a heel-cushioning pillar positioned under a heel center of the shoe upper corresponding to a wearer's calcaneus bone, the pillar including lateral, medial, and aft sides, and further including a depression in one of the sides of the pillar; and    a hard elastic stabilizing member for preventing pronation and supination, the stabilizing member having a hardness greater than the cushioning layer and extending from the medial side of the pillar and around the aft side and at least part of the lateral side of the pillar, the stabilizing member including a protrusion extending into the depression of the pillar, the protrusion and the depression positioned in alignment with a line of flexure of the heel region that extends diagonally from a point on the medial side margin of the sole aft of the heel center toward the lateral side margin of the sole forward of the heel center, thereby affecting flexure characteristics of the heel region and enhancing a medial support characteristic of the sole.    
     
     
         2 . The athletic shoe sole of  claim 1  in which the protrusion of the stabilizing member is sized to mate with the depression in the pillar for securely adhering thereto.  
     
     
         3 . The athletic shoe sole of  claim 1  in which: 
 the pillar extends downwardly from the wearer's foot to terminate at a bottom end; and  
 the pillar is tapered along its sides so that it is narrowest at its bottom end.  
 
     
     
         4 . The athletic shoe sole of  claim 1  in which the cushioning layer and the stabilizing member include a flex groove that extends across the sole in alignment with the line of flexure.  
     
     
         5 . The athletic shoe sole of  claim 1  in which the outsole includes an aft crash pad portion, a main heel portion positioned forward of the crash pad portion, and a thin section that extends diagonally across the heel region in alignment with the line of flexure to connect the crash pad portion to the main heel portion, the thin section facilitating manufacture of the athletic shoe and complementing the flexure characteristics of the midsole.  
     
     
         6 . The athletic shoe sole of  claim 5  in which the outsole includes a notch positioned under at least a portion of the protrusion of the stabilizing member and the depression of the pillar, the notch interposed between the crash pad portion and the main heel portion of the outsole.  
     
     
         7 . The athletic shoe sole of  claim 5  in which the thin section of the outsole includes an outsole flex channel in alignment with the line of flexure to promote flexing in the heel region along the line of flexure.  
     
     
         8 . The athletic shoe sole of  claim 7  in which the cushioning layer and the stabilizing member include respective first and second midsole flex channels corresponding to the outsole flex channel.  
     
     
         9 . The athletic shoe sole of  claim 1  in which the sole further comprises a shank stiffener positioned beneath the arch of the wearer's foot.  
     
     
         10 . The athletic shoe sole of  claim 9  in which the shank stiffener is bonded to the stabilizing member.  
     
     
         11 . The athletic shoe sole of  claim 1  in which the stabilizing member includes an upper joint surface, the cushioning layer includes a lower joint surface abutting the upper joint surface of the stabilizing member, and the upper and lower joint surfaces include interlocking wave surfaces extending along at least part of the lateral and medial sides of the sole.  
     
     
         12 . The athletic shoe sole of  claim 1  in which the cushioning layer is formed of an ethylvinylacetate (EVA) material having a hardness between approximately 50 and approximately 54 Asker C.  
     
     
         13 . The athletic shoe sole of  claim 1  in which the stabilizing member is formed of an ethylvinylacetate (EVA) material having a hardness between approximately 54 and approximately 58 Asker C.  
     
     
         14 . In an athletic shoe having a shoe upper and a sole, the sole including a heel region having lateral and medial sides, an improved sole comprising: 
 a soft elastic cushioning layer extending under the shoe upper; and    a hard elastic stabilizing member positioned beneath at least a portion of the cushioning layer for preventing pronation and supination, the stabilizing member having a hardness greater than the cushioning layer and extending generally around a central opening through which the cushioning layer extends downwardly from a heel center of the wearer beneath a calcaneus bone of the wearer, the stabilizing member including a protrusion extending into the opening in alignment with a line of flexure of the heel region that extends diagonally from a point on the medial side of the sole aft of the heel center toward the lateral side of the sole forward of the heel center, thereby affecting flexure characteristics of the heel region.    
     
     
         15 . The athletic shoe sole of  claim 14  in which: 
 the central opening in the stabilizing member extends in a generally vertical direction so that the central opening includes a top portion nearest the wearer's foot and a bottom portion opposite the top portion; and  
 the central opening tapers so that it is narrower at its bottom portion than at its top portion.  
 
     
     
         16 . The athletic shoe sole of  claim 14  in which: 
 the central opening in the stabilizing member extends in a generally vertical direction so that the central opening includes a top portion nearest the wearer's foot and a bottom portion opposite the top portion; and  
 the cushioning layer tapers where it extends through the central opening so that the cushioning layer is narrower at the bottom portion of the central opening than at the top portion of the central opening.  
 
     
     
         17 . The athletic shoe sole of  claim 14 , further comprising a flex groove extending across the cushioning layer and the stabilizing member in alignment with the line of flexure.  
     
     
         18 . The athletic shoe sole of  claim 14 , further comprising an outsole positioned under the cushioning layer and the stabilizing member, the outsole including an aft crash pad portion, a main heel portion positioned forward of the crash pad portion, and a thin section that extends diagonally across the heel region in alignment with the line of flexure to connect the crash pad portion to the main heel portion, the thin section facilitating manufacture of the athletic shoe and complementing the flexure characteristics of the sole.  
     
     
         19 . The athletic shoe sole of  claim 18  in which the outsole includes a notch positioned under at least a portion of the protrusion of the stabilizing member, the notch interposed between the crash pad portion and the main heel portion of the outsole.  
     
     
         20 . The athletic shoe sole of  claim 18  in which the thin section of the outsole includes an outsole flex channel in alignment with the line of flexure to promote flexing in the heel region along the line of flexure.  
     
     
         21 . The athletic shoe sole of  claim 20  in which the cushioning layer and the stabilizing member include respective first and second midsole flex channels corresponding to the outsole flex channel.  
     
     
         22 . The athletic shoe sole of  claim 14  in which the sole further comprises a shank stiffener positioned beneath the arch of the wearer's foot.  
     
     
         23 . The athletic shoe sole of  claim 22  in which the shank stiffener is bonded to the stabilizing member.  
     
     
         24 . The athletic shoe sole of  claim 14  in which the stabilizing member includes an upper joint surface, the cushioning layer includes a lower joint surface abutting the upper joint surface of the stabilizing member, and the upper and lower joint surfaces include interlocking wave surfaces extending along at least part of the lateral and medial sides of the sole.  
     
     
         25 . The athletic shoe sole of  claim 14  in which the cushioning layer is formed of an ethylvinylacetate (EVA) material having a hardness between approximately 50 and approximately 54 Asker C.  
     
     
         26 . The athletic shoe sole of  claim 14  in which the stabilizing member is formed of an ethylvinylacetate (EVA) material having a hardness between approximately 54 and approximately 58 Asker C.