Lace tightener incorporating SMA wire

A lace-tightening device for a shoe lace in a shoe comprising:

• a housing configured to be mounted within the shoe, the housing define at least one opening for receiving the opposite ends of the shoe lace;
• a rotating cam disposed within the housing and adapted for connection to the opposite ends of the shoe lace, the cam including an outer surface for receiving the shoe lace as the cam rotates;
• a drive gear affixed to said rotating cam for rotation in one direction to tighten the shoe lace connected to the rotating cam;
• a driven gear disposed within the housing;
• an idler gear in engagement between said drive gear and said driven gear to transmit rotation of said driven gear to rotation of said drive gear;
• a ratchet arm slidably disposed within the housing, said ratchet arm including linear teeth arranged to engage the teeth of the driven gear as the ratchet arm translates in a linear direction to rotate said driven gear and said drive gear, by way of said idler gear, in said one direction;
• and
• at least one shape memory alloy (SMA) wire attached at one end of the wire to the ratchet arm and at an opposite end of the wire to a controller, the controller configured to execute a power cycle to energize and de-energize the SMA wire so that the wire sequentially shrinks and returns to its original length to sequentially translate the ratchet arm in said linear direction while in engagement with said driven gear.