Electromechanical lock employing shape memory metal wire

• US 20050252260A1
• Filed: 05/11/2005
• Published: 11/17/2005
• Est. Priority Date: 05/12/2004
• Status: Active Grant

• Current Assignee: John Wun-Sing Chu
• Original Assignee: John Wun-Sing Chu
• Inventors: Chu, John Wun-Sing
• Granted Patent: US 7,406,846 B2
• Time in Patent Office: Days
• US Class Current: 70/278.700
• CPC Class Codes: E05B 47/0009 with thermo-electric actuators, e.g. heated bimetals
• CPC Class Codes: E05B 47/063 with a rectilinearly moveable blocking element
• CPC Class Codes: E05B 47/0634 with a pivotally moveable blocking element
• CPC Class Codes: E05B 63/14 Arrangement of several locks or locks with several bolts, e.g. arranged one behind the other locks having bolts with multiple head E05B15/108; with provision for latching E05B59/00, E05B61/00
• CPC Class Codes: Y10T 70/60 Systems
• CPC Class Codes: Y10T 70/70 Operating mechanism
• CPC Class Codes: Y10T 70/7068 Actuated after correct combination recognized [e.g., numerical, alphabetical, or magnet[s] pattern]
• CPC Class Codes: Y10T 70/7102 And details of blocking system [e.g., linkage, latch, pawl, spring]

Abstract

An electronic lock incorporating one or more shape memory metal wire segment as its electromechanical transducer. An electronic control circuit injects electrical current into the shape memory metal wire, causing it to heat up and contract. A gate is positioned by the action of the shape memory metal wire(s) to either allow or block the movement of a locking bolt that affect locking or unlocking. Millions of operational cycles are achieved by limiting the stretching of the shape memory metal wire at low temperature to small percentages of its total length. The design lends itself to miniaturization, with commensurate reduction in power consumption, that is useful to the evolution of future electronic locks.

Claims

1. An electronic lock comprising:

a shell having a bore therein;

a plug disposed in said bore of said shell;

a groove in either said shell or said plug;

a gate connected to said plug or said shell wherein when said gate enters said groove in a locked position, it limits movement of said plug relative to said shell;

a mechanism biasing said gate into the locked position;

a first shape memory metal wire segment that moves said gate from the locked position to an unlocked position away from the groove in response to an electrical current therein;

an electronic control circuit for injecting electrical current into said first shape memory metal wire segment to unlock the lock;

a second shape memory metal wire segment arranged to contract concurrently with opposite force to that caused by contraction of said first shape memory metal wire segment when ambient temperature rises above the transition temperature of said shape memory metal wires so that said gate is retained in the locked position by said mechanism.

2. An electronic lock as claimed in claim 1 wherein said mechanism is a spring.

3. An electronic lock as claimed in claim 1 wherein the second shape memory metal wire segment is arranged to contract concurrently with substantially equal force to that caused by contraction of said first shape memory metal wire segment when ambient temperature rises above the transition temperature of said shape memory metal wires.

4. An electronic lock comprising:

a shell having a bore therein;

a plug disposed in said bore of said shell;

a groove in either said shell or said plug;

a gating mechanism having a member connected to said plug or said shell,

wherein when said member enters said groove in a locked position, it limits movement of said plug relative to said shell;

a first device biasing said gating mechanism so that the member is in the locked position;

at least one first shape memory metal wire segment in non-elastic connection with said plug or said shell, said at least one first shape memory metal wire segment moving said gating mechanism or a component thereof from a first locking position to a second unlocking position in response to an electrical current in the at least one first shape memory metal wire segment and causing the member to be withdrawn from the locked position in the groove; and

an electronic control circuit for injecting electrical current into said at least one first shape memory metal wire segment to unlock the lock.

5. The lock of claim 4, wherein said gating mechanism is connected to the at least one first shape memory metal wire segment and to a second shape memory metal wire segment that contracts concurrently with substantially equal but opposite force to that caused by contraction of said first shape memory metal wire segment when ambient temperature rises above the transition temperature of said shape memory metal wire segments so that said member is retained in the locked position by said first device.

6. The lock of claim 4, wherein said plug and/or said shell rotate(s) or slide(s) relative to each other when the member is moved between the locked and unlocked positions.

7. The lock of claim 4, wherein said at least one first shape memory metal wire segment is stretched by not more than about 6% when said gating mechanism is moved between the first locking position and the second unlocking position.

8. The lock of claim 4, wherein said gating mechanism comprises a component including a gate that is moved by the at least one first shape memory metal wire segment and said first device between at least the first and second positions, wherein when the gate is in the first position, the member is prevented from moving away from a position inside the groove to a position substantially outside the groove, so that relative motion between said plug and said shell is limited, and when the gate is in the second position, the member is permitted to move from the locked position inside the groove to another position to allow relative motion between said plug and said shell.

9. The lock of claim 7, wherein said gating mechanism comprises a component including a gate of at least two enlarged sections and at least one smaller section between the at least two enlarged sections, and wherein when the gate is in the first position, at least one of the enlarged sections abuts the member and prevents the member from moving away from the groove, and when the gate is in the second position, the at least one smaller section is adjacent to the member and permits the member to move away from the groove.

10. The lock of claim 8, said gating mechanism further comprising at least one second device biasing said member away from said groove, wherein the at least one of the enlarged sections abutting said member prevents said member from moving away from said groove against action of the at least one second device, and the at least one second device moves said member away from said groove when said member is adjacent to the at least one smaller section.

11. The lock of claim 8, said gating mechanism further comprising a seesaw moving said gate between the first and second positions.

12. The lock of claim 10, said lock further comprising a second shape memory metal wire segment in non-elastic connection with said plug or said shell.

13. The lock of claim 11, in response to an electrical current in said second shape memory wire segment injected by said circuit in a bistable arrangement, said second shape memory wire segment moving said gate from the second position to the first position wherein said member is prevented from moving away from the locked position inside said groove.

14. The lock of claim 12, said first device biasing said seesaw at a pivot of said seesaw, to supply energy for moving said member between the locked and unlocked bistable positions.

15. The lock of claim 4, said first device biasing said gating mechanism or a component thereof into the first position.

16. The lock of claim 4, further comprising a pulley, wherein said at least one first shape memory metal wire segment is wrapped around said pulley.

18. The lock of claim 16, wherein said at least one first shape memory metal wire segment is in non-elastic connection with said plug or said shell.

19. The lock of claim 16, wherein said gating mechanism is connected to the at least one first shape memory metal wire segment and to a second shape memory metal wire segment that contracts concurrently with substantially equal but opposite force to that caused by contraction of said first shape memory metal wire segment when ambient temperature rises above the transition temperature of said memory metal wire segments so that said member is retained in the locked position by said first device.

20. The lock of claim 16, wherein said plug and/or said shell rotate(s) or slide(s) relative to each other when the member is moved between the locked and unlocked positions.

17. An electronic lock comprising:

a shell having a bore therein;

a plug disposed in said bore of said shell;

a groove in either said shell or said plug;

a gating mechanism having a member connected to said plug or said shell,

wherein when said member enters said groove in a locked position, it limits movement of said plug relative to said shell;

a first device biasing said gating mechanism;

at least one first shape memory metal wire segment moving said gating mechanism, so that said member is moved from the locked position to an unlocked position in response to an electrical current in the at least one first shape memory metal wire segment; and

an electronic control circuit for injecting electrical current into said at least one first shape memory metal wire segment to unlock the lock, wherein the at least one first shape memory metal wire segment is stretched by not more than 6% between the locked and the unlocked positions.

21. A method of electronically locking and unlocking, comprising:

(a) providing an electronic lock comprising;

a shell having a bore therein;

a plug disposed in said bore of said shell;

a groove in either said shell or said plug;

a gating mechanism having a member connected to said plug or said shell, wherein when said member enters said groove in a locked position, it limits movement of said plug relative to said shell;

a first device biasing said gating mechanism; and

at least one first shape memory metal wire segment moving said gating mechanism, so that said member is moved from the locked position to an unlocked position in response to an electrical current in at least one first shape memory metal wire segment; and

(b) injecting electrical current into said at least one first shape memory metal wire segment to unlock the lock, wherein the at least one first shape memory metal wire segment is stretched by not more than 6% between the locked and unlocked positions.

22. A method of electronically locking and unlocking, comprising:

(a) providing an electronic lock comprising;

a shell having a bore therein;

a plug disposed in said bore of said shell;

a groove in either said shell or said plug;

a gating mechanism having a member connected to said plug or said shell, wherein when said member enters said groove in a locked position, it limits movement of said plug relative to said shell;

a first device biasing said gating mechanism; and

at least one first shape memory metal wire segment moving said gating mechanism from the locked position to an unlocked position in response to an electrical current in the at least one first shape memory metal wire segment; and

(b) injecting electrical current into said at least one first shape memory metal wire segment to unlock the lock, wherein said providing includes connecting said at least one first shape memory metal wire segment non-elastically directly or indirectly with said plug or said shell.