GB2594832A

GB2594832A - Shape memory alloy actuator

Info

Publication number: GB2594832A
Application number: GB2109678.9A
Authority: GB
Inventors: Bunting Stephen; Flouris Andreas; Benjamin Simpson Brown Andrew; Scholz Marc-Sebastian; Carr Joshua; Van Wyk Peter; Powell Thomas
Original assignee: Cambridge Mechatronics Ltd
Current assignee: Cambridge Mechatronics Ltd
Priority date: 2018-12-10
Filing date: 2019-12-10
Publication date: 2021-11-10
Anticipated expiration: 2039-12-10
Also published as: WO2020120951A2; CN113168233A; WO2020120951A3; GB202215276D0; GB2594832B; GB2608769A; GB202109678D0

Abstract

The present techniques generally relate to shape memory alloy actuators, and for methods of manufacturing such SMA actuators. We describe a shape memory alloy (SMA) actuator comprising a static element (104); a moveable element (106) which is moveable relative to the static element; and a plurality of SMA wires (108) which are each connected to one or both of the static element and the moveable element and which on contraction cause movement of the moveable element. At least one connector (110a, 110c), preferably a crimp connector, connects at least two of the plurality of SMA wires (108) to at least one of the static element and the moveable element.

Claims

1. A shape memory alloy (SMA) actuator comprising a static element; a moveable element which is moveable relative to the static element; a plurality of SMA wires which are each coupled to one or both of the static element and the moveable element and which on contraction cause movement of the moveable element; and a coupling element which couples at least two wires from the plurality of SMA wires to one of the static element and the moveable element.

2. The SMA actuator of claim 1, wherein the coupling element comprises a crimp connector which holds the at least two wires.

3. The SMA actuator of claim 2, wherein the crimp connector holds between two and six wires.

4. The SMA actuator of claim 2 or claim 3, wherein the crimp connector has a width of between 500mGh and 750mGh.

5. The SMA actuator of any one of claims 2 to 4, comprising a first crimp connector connecting one end of each of the at least two wires to the static or moveable element and a second crimp connector connecting the other end of each of the at least two wires to the static or moveable element.

6. The SMA actuator of claim 5, wherein the first crimp connector is the same type as the second crimp connector.

7. The SMA actuator of claim 5 or claim 6, comprising multiple pairs of first and second crimp connectors with each pair of crimp connectors connecting each of at least two wires to one or both of the static element and the moveable element.

8. The SMA actuator of claim 7, comprising a first pair of crimp connectors which connect each of a first set of at least two wires to the moveable element and a second pair of crimp connectors which connect each of a second set of at least two wires to the moveable element, wherein when the first set of at least two wires contract the moveable element is moved in a first direction and when the second set of at least two wires contract the moveable element is moved in the opposite direction to the first direction.

9. The SMA actuator of claim 7, comprising a first pair of crimp connectors which connect each of a first set of at least two wires to the moveable element and a second pair of crimp connectors which connect each of a second set of at least two wires to the moveable element, wherein when the wires connected to the first pair and the second pair of crimp connectors contract the moveable element is moved in one direction.

10. The SMA actuator of any one of claims 5 to 7, wherein the first crimp connectors connect one end of the at least two wires to a first region of the static element, the second crimp connectors connect the other end of the at least two wires to a second region of the static element, the at least two wires generally extend in a first direction, and when the plurality of SMA wires contract the moveable element moves in a direction that is at an acute angle greater than zero to the first direction.

11. The SMA actuator of any one of claims 5 to 10, wherein the at least two SMA wires do not cross in between the first and second crimps.

12. The SMA actuator of any one of claims 5 to 10, wherein the at least two SMA wires do not cross inside the crimp connector and cross in between the first and second crimps.

13. The SMA actuator of any one of claims 2 to 12, wherein the at least two SMA wires do not cross inside the crimp connector.

14. The SMA actuator of any one of claims 2 to 13, wherein the at least two wires generally extend parallel to each other between the crimp connectors.

15. The SMA actuator of claim 1, wherein the coupling element comprises at least two adjacent crimp connectors each of which holds a single wire.

16. The SMA actuator of claim 15, wherein the at least two adjacent crimp connectors are vertically aligned.

17. The SMA actuator of claim 15, wherein the at least two adjacent crimp connectors are laterally and/or vertically offset from each other.

18. The SMA actuator of claim 1, wherein the coupling element is a welded component that is welded to the at least two wires.

19. The SMA actuator of claim 1, wherein the coupling element comprises a protruding element around which the at least two wires are looped.

20. The SMA actuator of any preceding claims, wherein the coupling element provides a direct connection between the at least two wires and one of the static element and the moveable element.

21. The SMA actuator of any preceding claims, wherein the coupling element couples the at least two wires to an intermediate component to provide an indirect connection between the at least two wires and one of the static element and the moveable element.

22. The SMA actuator of any preceding claim, further comprising at least one heatsink adjacent the plurality of SMA wires.

23. The SMA actuator of claim 22, wherein the at least one heatsink is at a distance from the plurality of wires which is less than five times the diameter of each wire.

24. The SMA actuator of claim 22 or claim 23, wherein the at least one heatsink is touching the plurality of SMA wires.

25. The SMA actuator of any one of claims 22 to 24, wherein the at least one heatsink and/or the plurality of wires are moveable relative to one another between a first position in which the heatsink is adjacent or touching the plurality of wires and a second position in which the heatsink is further from the plurality of wires.

26. A haptic assembly comprising a touchable component and the SMA actuator of any one of claims 1 to 25, wherein when a user presses the touchable component, the actuator module is activated to provide haptic feedback to the user by moving the touchable component using the moveable element.

27. A latch comprising the SMA actuator of any one of claims 1 to 25.

28. A method of manufacturing an SMA actuator, the method comprising: feeding a plurality of SMA wires into an open crimp connector; closing the crimp connector; and trimming any excess wire.

29. The method of claim 28, comprising using a guide wheel to guide the SMA wires into the open crimp connector.

30. The method of claim 28 or claim 29, comprising : feeding the plurality of SMA wires into a further open crimp connector; closing the further crimp connector; and controlling the tension in each of the plurality of SMA wires and/or the length of each of the plurality of SMA wires between the crimp connectors while closing at least one of the crimp connectors, so that each of the plurality of wires has substantially the same tension and/or length between the crimp connectors.

31. The method of claim 30, comprising arranging the plurality of SMA wires to each follow an equivalent path while closing the at least one crimp connector.