Energy storage and return spring

Abstract

A spring shoe, and also in particular a spring, as well as a method of returning energy to a user, are provided. In one embodiment, a method and apparatus stores foot strike energy and releases it after a slight delay, when it will exert a force on the user which includes a forward component. This is accomplished in an embodiment by a spring in the sole which has a decreasing spring force, such that the force required to compress the sole decreases for all or part of the compression displacement as the spring is compressed.

1 . A spring shoe, comprising:
 a sole having a heel and a forefoot;   an upper secured to the sole;   a spring set at least partly in the sole, the spring having a spring range of travel under compression of the sole and spring by a foot supported by the spring shoe;   the spring having a spring rate that varies with the compression of the spring to provide a reducing force resisting compression over at least a portion of the spring range of travel as the spring compresses; and   a biased damper in the sole, the biased damper being oriented to oppose compression of the sole as the spring compresses towards maximum compression.   
     
     
         2 . The spring shoe of  claim 1  in which the spring range of travel extends between full compression of the spring and no compression of the spring and the spring is configured to provide a reducing force resisting compression of the spring as the spring approaches full compression. 
     
     
         3 . The spring shoe of  claim 1  in which the spring is configured to provide an increasing force resisting compression as the sole approaches full compression of the sole. 
     
     
         4 . The spring shoe of  claim 1  in which the spring range of travel extends between end points and the spring has a spring rate that is zero at a point between the end points of the range of travel and the force of the spring resisting compression decreases as the spring compresses beyond the point of zero spring rate. 
     
     
         5 . The spring shoe of  claim 1  in which the biased damper has a damping range of travel, and the damping range of travel is less than the spring range of travel. 
     
     
         6 . The spring shoe of  claim 5  in which the biased damper comprises an energy dissipating compressible material. 
     
     
         7 . The spring shoe of  claim 5  in which the biased damper comprises an energy dissipating deformable material. 
     
     
         8 . The spring shoe of  claim 4  in which the biased damper comprises an air chamber having conduits allowing flow of air into and out of the air chamber. 
     
     
         9 . The spring shoe of  claim 8  in which the air chamber has air flow regulator elements that restrict air flow out of the air chamber more than air flow into the air chamber. 
     
     
         10 . The spring shoe of  claim 1  in which the spring comprises a rigid element and an elastic element connected to the rigid element to oppose flattening of at least one of the rigid element and the elastic element in the sole. 
     
     
         11 . The spring shoe of  claim 10  where the rigid element is loaded in compression, and the elastic element is loaded in tension. 
     
     
         12 . The spring shoe of  claim 10  in which the elastic element is arranged in tension to resist flattening of the rigid element in the sole. 
     
     
         13 . The spring shoe of  claim 10  in which the elastic element is arranged in compression to resist flattening of the spring in the sole. 
     
     
         14 . The spring shoe of  claim 12  in which the rigid element is arched, has an apex and has at least a hinge or is flexible at the apex to allow the rigid element to flatten upon force applied to the apex. 
     
     
         15 . The spring shoe of  claim 14  in which the elastic element comprises a connected periphery of the rigid element. 
     
     
         16 . The spring shoe of  claim 14  in which the rigid element is pre-stressed at full compression to return toward an uncompressed state. 
     
     
         17 . The spring shoe of  claim 13  in which the rigid element is air sealed. 
     
     
         18 . The spring shoe of  claim 10  in which the rigid element comprises a conical disk. 
     
     
         19 . The spring shoe of  claim 18  in which the conical disk incorporates expansion slots. 
     
     
         20 . The spring shoe of  claim 19  in which the expansion slots are defined by ridges and at least some of the slots are wider in the circumferential direction than the ridges. 
     
     
         21 - 29 . (canceled) 
     
     
         30 . The spring shoe of  claim 10  in which the rigid element forms a ridge. 
     
     
         31 . The spring shoe of  claim 30  in which the rigid element has at least a living hinge. 
     
     
         32 . (canceled) 
     
     
         33 . The spring shoe of  claim 10  in which the elastic element comprises an acetal resin. 
     
     
         34 . (canceled) 
     
     
         35 . The spring shoe of  claim 1  in which the spring has maximum force resisting compression at greater than 30% of the spring range of travel measured from zero compression of the spring. 
     
     
         36 - 93 . (canceled)