Dynamic footwear sole construction

Abstract

A dynamic footwear midsole has an upper layer and a lower layer that are connected by a group of heel slats and a group of forepart slats, each slat being connected at hinge regions to the upper and lower layers. The slats in each group are arranged in generally paralleling planes with the heel slats and forepart slats being arranged to cause one group to collapse as the other group expands. An arch segment is provided at the midportion of the upper layer is constructed and supported by an arch support structure that enables the upper layer and arch support structure to rock, as a unit, about a pivot region at the lower end of the support structure.

1 . A footwear midsole comprising:
 an upper layer;   a lower layer spaced from the upper layer, the layers being distinct from each other;   each of the upper layer and lower layer having a heel portion, a midportion and a forepart portion;   the upper layer having an arched segment at the midportion;   a relatively stiff arch support structure at the midportion of the midsole, the arch support structure supporting the arched segment and extending between and connected to the upper and lower layers and;
 a plurality of generally planar heel slats extending transversely between and hingedly connected to the heel portions of the upper and lower layers; 
 a plurality of generally planar forepart slats extending transversely between and hingedly connected to the forepart portions of the upper and lower layers; 
 the arch support structure being of sufficient strength to present greater resistance to heightwise compression than the heel and forepart portions of the midsole, the arch support structure having a lower portion attached to the lower layer to define a pivot region about which the arch support structure may rock, as a unit, together with the upper layer, toeward and heelward about the pivot region as a stride progresses. 
   
     
     
         2 . The midsole as defined in  claim 1  further comprising:
 the heel slats being inclined in an upward and heelward direction; and 
 the forepart slats being inclined in an upward and toeward direction. 
 
     
     
         3 . The midsole as defined in  claim 1  further comprising:
 the upper and lower layers and the slats being formed as a unitary, one-piece structure. 
 
     
     
         4 . The midsole as defined in  claim 2  further comprising:
 the upper and lower layers and the slats being formed as a unitary, one-piece structure. 
 
     
     
         5 . The midsole as defined in  claim 2  further comprising:
 the arched segment extending from the most toeward of the heel slats to the most heelward of the heel slats. 
 
     
     
         6 . The midsole as defined in  claim 5  further comprising:
 the most toeward of the heel slats being attached to the upper layer at the heelward portion of the arched segment and the most heelward of the forepart slats being attached to the upper layer at the toeward portion of the arched segment. 
 
     
     
         7 . The midsole as defined in  claim 6  further comprising:
 the most toeward of the heel slats and the most heelward of the forepart slats being thicker and having less flexible hinge regions than the other slats, the most toeward of the heel slats and the most heelward of the forepart slats comprising the arch support structure. 
 
     
     
         8 . The midsole as defined in  claim 6  wherein the support structure for the arch support further comprises:
 at least one longitudinally and heightwise extending support brace connected between the upper layer and the lower layer and between the most heelward slat of the forepart slats and the most toeward of the heel slats. 
 
     
     
         9 . The midsole as defined in  claim 1  and having a centerline extending between a heel extremity and a toe extremity of the midsole and further comprising:
 the plurality of heel slats and the plurality of forepart slats extending at a non-perpendicular angle to the centerline with the medial ends of the slats being toeward of the their lateral ends. 
 
     
     
         10 . The midsole as defined in  claim 9  wherein the angle is between about ten and twenty degrees. 
     
     
         11 . The midsole as defined in  claim 2  wherein the plurality of heel slats are arranged in generally paralleling planes and the plurality of forepart slats are arranged in generally paralleling planes. 
     
     
         12 . The midsole as defined in  claim 1  wherein the upper and lower layers and longitudinally spaced plurality of heel slats and longitudinally spaced plurality of forepart slats define a plurality of hollow prism-shaped cells, each being defined by a pair of adjacent slats and a segment of each of the upper and lower layers. 
     
     
         13 . The midsole as defined in  claim 2  wherein the upper layer is sufficiently stiff to enable the upper layer to rock about the pivot region of the arch support structure in heelward and toeward directions. 
     
     
         14 . The midsole as defined in  claim 12  wherein the upper layer is sufficiently stiff to prevent distortion of the segments of the upper layer in response to rocking of the upper layer about the pivot region. 
     
     
         15 . The midsole as defined in  claim 1  wherein the arched segment and the arch support structure define a generally triangular configuration with a lower apex that defines a pivot region that functions as a fulcrum about which the upper layer and support structure can pivot. 
     
     
         16 . A footwear midsole having a heel portion, a midportion and a forepart portion and comprising:
 an upper layer;   a lower layer spaced from the upper layer;   each of the upper and the lower layer having a heel portion, a midportion and a forepart portion;   the midportion of the upper layer being formed to define an arched segment;   a bracing structure extending between and connected to the upper and lower layers and supporting the arched segment, the lower end of the bracing structure being hingedly attached to the lower layer at a fulcrum region to enable the bracing structure and upper layer to pivot about the fulcrum region in heelward and toeward directions;   a plurality of generally planar heel slats extending transversely between and hingedly connected to the heel portions of the upper and lower layers;   a plurality of generally planar forepart slats extending transversely between and hingedly connected to the forepart portions of the upper and lower layers.   
     
     
         17 . The footwear midsole as defined in  claim 16  further comprising:
 the heel slats being inclined in an upward and heelward direction; and the forepart slats being inclined in an upward and toeward direction. 
 
     
     
         18 . The footwear midsole as defined in  claim 17  further comprising:
 each pair of adjacent slats and segments of the upper and lower layers hingedly connected to those slats defining a four-bar linkage. 
 
     
     
         19 . The footwear midsole as defined in  claim 18  wherein the four-bar linkages oscillate between expanded and collapsed configurations as the upper layer pivots about the fulcrum region. 
     
     
         20 . The footwear midsole as defined in  claim 19  wherein the four-bar linkages oscillate in opposite directions as the upper layer pivots. 
     
     
         21 . An article of footwear comprising:
 an upper;   a midsole as defined in  claim 1  attached to the upper; and   an outsole attached to the lower layer of the midsole.