Shape memory alloy based linear actuator assembly

Patent metadata

Field	Value
Publication number	US-9267494-B2
Application number	US-201213676164-A
Country	US
Kind code	B2
Filing date	Nov 14, 2012
Priority date	Nov 14, 2012
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

A linear motion device includes a rod extending along a longitudinal axis, and a plurality of actuator units. Each of the plurality of actuator units includes at least one Shape Memory Alloy (SMA) element that is attached to a coupling mechanism. The at least one SMA element of each if the plurality of actuator units moves the coupling mechanism along the longitudinal axis, and into grasping engagement with the rod. Each actuator unit moves the rod a unit movement distance along the longitudinal axis in response to a control signal. The plurality of actuator units are actuated repeatedly in a cyclic order to move the rod in a continuous linear motion a distance greater than the unit movement distance of each of the plurality of actuator units.

First claim

The invention claimed is:

1. A linear motion device comprising:
a rod extending along a longitudinal axis; and
a plurality of actuator units, with each of the plurality of actuator units including at least one Shape Memory Alloy (SMA) element attached to a coupler, wherein the at least one SMA element of each of the plurality of actuator units moves the coupler along the longitudinal axis and into grasping engagement with the rod to move the rod a unit movement distance along the longitudinal axis in response to a control signal;
wherein the plurality of actuator units are actuated repeatedly in a synchronous order to move the rod in a continuous linear motion a distance greater than the unit movement distance of each of the plurality of actuator units;
wherein each of the plurality of actuator units includes a first coupler and a second coupler disposed on opposite sides of the rod; and
wherein the at least one SMA element includes a connecting SMA element extending between and attached to both the first coupler and the second coupler and configured to contract to draw the first coupler and the second coupler together into grasping engagement with the rod in response to the signal.

2. A linear motion device as set forth in claim 1 wherein the at least one SMA element of each of the plurality of actuator units contracts in response to the control signal to move the coupler.

3. A linear motion device as set forth in claim 1 wherein the at least one SMA element of each of the plurality of actuator units elongates in response to the cessation of the control signal to release the coupler from the grasping engagement with the rod and allow the coupler to return to a neutral position.

4. A linear motion device as set forth in claim 1 wherein the at least one SMA element of each of the plurality of actuator units is operable to move the coupler and the rod in both a first direction parallel to the longitudinal axis, and a second direction parallel to the longitudinal axis, wherein the first direction is opposite the second direction.

5. A linear motion device as set forth in claim 4 wherein the at least one SMA element includes a first SMA element attached to the coupler for moving the coupler in the first direction, and a second SMA element attached to the coupler for moving the coupler in the second direction.

6. A linear motion device as set forth in claim 1 wherein each of the plurality of actuator units includes at least one spring.

7. A linear motion device as set forth in claim 1 wherein at least one of the rod and the coupler include a friction feature.

8. A linear motion device as set forth in claim 1 wherein each of the plurality of actuator units includes a housing, with the rod and the coupler moveable relative to the housing.

9. A linear motion device as set forth in claim 8 wherein the coupler is coupled to the housing.

10. A linear motion device as set forth in claim 1 wherein a first group of the plurality of actuator units may be actuated simultaneously to increase a moving force applied to the rod.

11. A linear motion device as set forth in claim 1 wherein the coupler includes a spring member.

12. A linear motion device as set forth in claim 1 wherein the coupler includes a lever arm.

13. A linear motion device as set forth in claim 1 wherein each of the plurality of actuator units may default to a normally engaged position disposed in grasping engagement with the rod, or a normally disengaged position not disposed in grasping engagement with the rod.

14. A linear actuator assembly for a linear motion device, the linear actuator assembly comprising:
a plurality of actuator units, with each of the actuator units including:
a housing;
a coupler; and
at least one Shape Memory Alloy (SMA) element attached to the coupler;
wherein the at least one SMA element moves the coupler from a neutral position along a longitudinal axis and into grasping engagement with a rod to move the rod a unit movement distance along the longitudinal axis in response to a control signal;
wherein the at least one SMA element of each of the plurality of actuator units contracts in response to the control signal to move the coupler; and
wherein the at least one SMA element of each of the plurality of actuator units elongates in response to the cessation of the control signal to release the coupler from the grasping engagement with the rod and allow the coupler to return to the neutral position;

wherein the plurality of actuator units are actuated repeatedly in a synchronous order to move the rod in a continuous linear motion a distance greater than the unit movement distance of each of the plurality of actuator units; and
wherein each of the plurality of actuator units includes a first coupler and a second coupler disposed on opposite sides of the rod, and wherein the at least one SMA element includes a connecting SMA element extending between and attached to both the first coupler and the second coupler and configured to contract to draw the first coupler and the second coupler together into grasping engagement with the rod in response to the signal.

15. A linear actuator assembly as set forth in claim 14 wherein each of the plurality of actuator units includes at least one spring.

16. A linear actuator assembly as set forth in claim 14 wherein each of the plurality of actuator units includes a housing, with the rod and the coupler moveable relative to the housing, and with the coupler coupled to the housing.

17. A linear actuator assembly as set forth in claim 14 wherein the at least one SMA element includes a first SMA element attached to the coupler for moving the coupler in a first direction parallel to the longitudinal axis, and a second SMA element attached to the coupler for moving the coupler in a second direction parallel to the longitudinal axis, wherein the first direction is opposite the second direction.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Suissa Avshalom
• Raz Guy

Classifications

• F03G7/06143

  Wires · CPC title

• F03G7/066

  Actuator control or monitoring · CPC title

• F03G7/0636

  with several elements connected in parallel · CPC title

• F03G7/0614 Primary

  using shape memory elements · CPC title

• F03G7/06

  using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like (using thermal expansion of non-vaporising liquids F01K) · CPC title