Quick-return active material actuator

• US 9,234,509 B2
• Filed: 05/24/2011
• Issued: 01/12/2016
• Est. Priority Date: 05/24/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Mankame, Nilesh D., Skurkis, Richard J., Kramarczyk, Mark A., Alexander, Paul W.
• Primary Examiner(s): Pereiro, Jorge
• Assistant Examiner(s): THIEDE, PAUL WILLIAM
• Application Number:
  US13/114,731
• Publication Number:
  US 20120297763A1
• Time in Patent Office: 1,694 Days
• Field of Search: 605/27, 605/28, 605/29
• US Class Current: 1/1
• CPC Class Codes: F03G 7/065 using a shape memory element
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines

Abstract

A quick-return active material actuator adapted for more rapidly returning a load, so as to reduce the de-actuation time of a system, includes in a first aspect a thermally activated active material actuation element drivenly coupled to the load, an active material de-actuation element drivenly coupled to the load non-antagonistic to the actuation element, and a reconfigurable mechanism interconnecting the elements and load, wherein the de-actuation element and mechanism are cooperatively configured to return the load while the actuation element is still activated, and, in a second aspect a thermally activated active material actuation element drivenly coupled to a biased load and operable to autonomously release, so that the load is caused to be returned while the actuation element is still activated, and subsequently re-engage the load.

Claims

1. A quick-return actuator comprising:

an actuating SMA wire operable to undergo a reversible change in length that includes a first change in length when exposed to a first external signal so as to be in a first activated state, and drivenly connectable to a load such that the first change causes the load to move from a home position to a first position;

a de-actuating SMA wire non-antagonistic to the actuating SMA wire, the de-actuating SMA wire operable to undergo a reversible change in length that includes a second change in length when exposed to a second external signal so as to be in a second activated state, and drivenly connectable to the load such that the second change causes the load to move from the first position to a second position; and

an external member having an insulated interior space with the de-actuating SMA wire disposed therein, wherein;

the de-actuating SMA wire is to be insulated from the first external signal, thereby rendering the de-actuating SMA wire unresponsive to the first external signal;

the second external signal is allowed to pass to the de-actuating SMA wire;

wherein;

the actuating SMA wire is in a first de-activated state when the actuating SMA wire undergoes a reversal of the first change in length;

the de-actuating SMA wire is in a second de-activated state when the de-actuating SMA wire undergoes a reversal of the second change in length; and

the actuating SMA wire and the de-actuating SMA wire are cooperatively configured such that the actuating SMA wire is operable to re-undergo the first change in length when re-exposed to the first external signal to move the load to the first position when;

the load is in the second position;

the actuating SMA wire is in the first de-activated state; and

the de-actuating SMA wire is in the second de-activated state.

2. The actuator as claimed in claim 1, further comprising a reconfigurable mechanism drivenly coupled to the actuating SMA wire and the load, and configured to shift from a first configuration to a second configuration as a result of the second change in length, such that the load achieves the second position as a result of shifting the reconfigurable mechanism to the second configuration.

3. The actuator as claimed in claim 2, wherein the reconfigurable mechanism includes the external member and an internal member that are mutually relatively translatable, the external member is drivenly coupled to the de-actuating SMA wire, such that the second change in length causes the external member to translate relative to the internal member, and the reconfigurable mechanism is caused to shift to the second configuration by translating the external member.

4. The actuator as claimed in claim 3, wherein at least a portion of the external member is tubular and defines the interior space, and at least a portion of the internal member is disposed within the interior space.

5. The actuator as claimed in claim 3, wherein the reconfigurable mechanism further includes at least one adjustable stop configured to impose a prescribed pre-load on a spring and to constrain the relative motion of the translatable internal member and the translatable external member.

6. The actuator as claimed in claim 3, wherein the reconfigurable mechanism further includes a biasing member drivenly coupled to the internal member and the external member, so as to produce a biasing force thereupon, wherein the force drives the reconfigurable mechanism towards the first configuration, and the second change is configured to overcome the biasing force and cause the external member to translate relative to the internal member.

7. The actuator as claimed in claim 6, wherein the de-actuating SMA wire, the internal member, the external member, and the biasing member are cooperatively configured such that the biasing member imposes a prescribed pre-load on the external member when the load is in the home position.

8. The actuator as claimed in claim 2, wherein the reconfigurable mechanism includes a first pivot arm and a second pivot arm, each defining a respective pivot axis.

9. The actuator as claimed in claim 8, wherein:

each respective pivot axis defines an upper section and a lower section of the respective arms;

the actuating SMA wire and de-actuating SMA wire are drivenly connected to one of the upper section and the lower section; and

the actuator further comprises an overload spring drivenly connected to the other of the upper section and the lower section.

10. The actuator as claimed in claim 1, wherein:

the de-actuating SMA wire has an available functional length and an available strain; and

the actuator further comprises at least one pulley entraining the de-actuating SMA wire, so as to bend the de-actuating SMA wire and increase the available strain of the de-actuating SMA wire.

11. The actuator as claimed in claim 10, wherein the at least one pulley and the de-actuating SMA wire are cooperatively configured, so as to provide mechanical advantage to the de-actuating SMA wire.

12. The actuator as claimed in claim 1, further comprising:

a power source communicatively coupled to the de-actuating SMA wire, and operable to generate the second external signal; and

a controller communicatively coupled to the actuating SMA wire, the de-actuating SMA wire, and the power source, and programmably configured to control the second external signal based on inferred states, internal logic, or a combination thereof.

13. The actuator as claimed in claim 12, further comprising at least one sensor or input device communicatively coupled to the controller, and operable to determine an event or condition and to deliver an input to the controller when the event or condition is determined, wherein the at least one sensor or input device and the controller are cooperatively configured to manipulate the first external signal, the second external signal, or both the first external signal and the second external signal when the event or condition is determined.

14. The actuator as claimed in claim 1, wherein the actuating SMA wire presents a bow-string configuration, and engages the load medially.

15. The actuator as claimed in claim 1 wherein the first external signal and the second external signal are separate thermal signals.

16. The actuator as claimed in claim 1 wherein the second position is the home position.

17. A quick-release actuator adapted for autonomously releasing a biased load, the quick-release actuator comprising:

a fixed structure configured to support a driven member for relative motion in a horizontal direction between the fixed structure and the driven member, the fixed structure including a sloped surface;

the driven member including a chamfered edge and operable to engage the load, the chamfered edge of the driven member configured to be slideably engaging with the sloped surface of the fixed structure so the fixed structure supports relative motion between the driven member and the fixed structure along a direction of travel of the driven member, the sloped surface and the chamfered edge each having an angle of measure relative to the horizontal direction from about 20 degrees to about 45 degrees; and

an SMA wire operably drivenly coupled to the driven member and operable to undergo a reversible change in length that includes a first change in length when exposed to an external signal, wherein;

when the SMA wire is exposed to the external signal, the first change in length occurs to the SMA wire such that the load is moved from a home position to a first position such that the chamfered edge of the driven member slideably moves along the sloped surface of the fixed structure; and

the first change of length of the SMA wire, the sloped surface, and the chamfered edge collectively cooperating together to allow the driven member to autonomously disengage from the load when the load attains the first position so that the load is able to return back to the home position.

18. The actuator as claimed in claim 17, further comprising a biasing member drivenly coupled to the load, and configured to return the load to the home position, when the driven member and load are disengaged.

19. The actuator as claimed in claim 18, wherein the biasing member includes a spring drivenly coupled to the load.

20. The actuator as claimed in claim 17, further comprising a reset mechanism drivenly coupled to the driven member, antagonistic to the SMA wire, and configured to autonomously re-engage the driven member and the load when the first change in length of the SMA wire is reversed and the load returns to the home position.

21. The actuator as claimed in claim 20, wherein the reset mechanism includes a spring drivenly coupled to the driven member.