Portable energy storage devices and methods

Abstract

Devices and methods which store and selectively release relatively substantial amounts of energy for enabling individuals to undertake superior performance in locomotion and other physical activities. The different embodiments include a hyperelastic SMA element which stores and releases energy in a differential pulley set, in a hinged knee, and in a pogo stick.

1 . An energy storage device comprising a hyperelastic shape memory alloy element which changes to one shape while storing energy responsive to a stress, and a structure which applies the stress to the element, the structure being selected from the group consisting of a differential pulley mechanism, a knee brace and a pogo stick.  
   
   
       2 . A device as in  claim 1  in which the hyperelastic element is a single crystal.  
   
   
       3 . A device as in  claim 1  in which the hyperelastic element is a single crystal of copper aluminum nickel.  
   
   
       4 . A device as in  claim 3  in which the alloy contains about 80% Cu, 12% Al, and 3% Ni by weight.  
   
   
       5 . A device as in  claim 1  in which the pulley ratio of the differential pulley is about 4/3.  
   
   
       6 . A device as in  claim 1  in which the hyperelastic element elongates by more than 8 percent strain responsive to the stress  
   
   
       7 . A method of storing and selectively releasing energy in a device that can be carried by an individual, the method comprising the steps of providing a hyperelastic shape memory alloy element, applying a stress to the element which stores energy in the element which when release is sufficient to enable the individual to undertake superior performance in locomotion and other physical activities, and releasing the energy.  
   
   
       8 . A method as in  claim 7  in the step of applying the stress is carried out by elongating the element while storing energy, and the step of releasing the energy is carried out by enabling the element to contract.