Lace tightener incorporating SMA wire

1. 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 driven gear disposed within the housing;

a one-way clutch rotatably coupling said driven gear to said rotating cam so that rotation of said driven gear in one direction rotates said cam in said one direction, thereby tightening the shoe lace connected to the rotating cam;

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 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 deenergize 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.

2. The lace-tightening device of claim 1 , wherein the ratchet arm is elongated with one end slidably supported within said housing.

3. The lace-tightening device of claim 2 , wherein said one opposite end of said ratchet arm is slidably supported on an elongated rod, and a spring arrangement is concentrically disposed on said rod to exert a force on said one end of said ratchet arm in a direction opposite said linear direction.

4. The lace-tightening device of claim 1 , wherein the teeth of said driven gear and said teeth of said ratchet arm are configured so that said teeth of said ratchet arm only engage the teeth of the driven gear when the ratchet arm moves in said linear direction.

5. The lace-tightening device of claim 1 , wherein said controller includes a control button mounted to the shoe to be manually actuated to activate said controller to execute the power cycle.

6. The lace-tightening device of claim 1 , wherein said one-way clutch is configured to be released to permit the driven gear and thus said rotating cam to be rotated in a direction opposite said one direction.

7. The lace-tightening device of claim 1 , further comprising:

a second ratchet arm slidably disposed within the housing, said second ratchet arm including linear teeth arranged to engage the teeth of the driven gear as the second ratchet arm translates in a linear direction to rotate said driven gear in said one direction; and

a second SMA wire attached at one end of the wire to said second ratchet arm and at an opposite end of the wire to said controller,

wherein said controller is configured to alternate executing the power cycle between the two ratchet arms.

8. The lace-tightening device of claim 1 , wherein said housing defines a channel on the outside surface thereof and said at least one SMA wire is wound around the outside surface of the housing within said channel.

9. The lace-tightening device of claim 1 , wherein the SMA wire is formed of Nitinol.

10. The lace-tightening device of claim 1 , wherein the device is sized to be disposed within the sole of the shoe.

11. A device for tightening an elongated lace having opposite ends, the device comprising:

a housing defining at least one opening for receiving at least one of the opposite ends of the lace;

a rotating cam disposed within the housing and adapted for connection to at least one of the opposite ends of the lace, the cam including an outer surface for receiving the lace as the cam rotates;

a driven gear disposed within the housing;

a one-way clutch rotatably coupling said driven gear to said rotating cam so that rotation of said driven gear in one direction rotates said cam in said one direction, thereby pulling the lace connected to the rotating cam;

a ratchet arm slidably disposed within the housing, said ratchet arm including a line of teeth arranged to engage the teeth of the driven gear as the ratchet arm translates within the housing to rotate said driven 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 deenergize the SMA wire so that the wire sequentially shrinks and returns to its original length to sequentially translate the ratchet arm while in engagement with said driven gear.

12. The device of claim 11 , wherein said one-way clutch is configured to be released to permit the driven gear and thus said rotating cam to be rotated in a direction opposite said one direction.

13. The device of claim 11 , further comprising:

a second ratchet arm slidably disposed within the housing, said second ratchet arm including a line of teeth arranged to engage the teeth of the driven gear as the second ratchet arm translates to rotate said driven gear in said one direction; and

a second SMA wire attached at one end of the second wire to said second ratchet arm and at an opposite end of the wire to said controller,

wherein said controller is configured to alternate executing the power cycle between the two ratchet arms.