GB2594663A

GB2594663A - Shape memory alloy actuator

Info

Publication number: GB2594663A
Application number: GB2110817.0A
Authority: GB
Inventors: Benjamin Simpson Brown Andrew; Carr Joshua; Scholz Marc-Sebastian
Original assignee: Cambridge Mechatronics Ltd
Current assignee: Cambridge Mechatronics Ltd
Priority date: 2019-01-23
Filing date: 2020-01-23
Publication date: 2021-11-03
Anticipated expiration: 2040-01-23
Also published as: CN216429851U; GB201900950D0; GB202110817D0; GB2594663B; WO2020152473A1

Abstract

The present application relates to shape memory alloy actuators. We describe a shape memory alloy (SMA) actuator comprising a static element (104a, 104b); a moveable element (106) which is moveable relative to the static element; and a plurality of SMA wire sections (108a, 108b). Each of the plurality of SMA wire sections (108a, 108b) are coupled to the static element (104a, 104b) and the moveable element (106) and on contraction cause the moveable element to move in a direction of movement. An axis of each of the plurality of SMA wire sections is generally at an acute angle to the direction of movement of the moveable element which are connected to both the static element and the moveable element and which on contraction cause movement of 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 wire sections each of which are coupled to the static element and the moveable element and which on contraction cause the moveable element to move in a direction of movement; and wherein an axis of each of the plurality of SMA wire sections is generally at an acute angle to the direction of movement of the moveable element.

2. The SMA actuator of claim 1, wherein the plurality of SMA wire sections are electrically connected to form at least one electrical path wherein each electrical path comprises at least two SMA wire sections which are electrically connected in series.

3. The SMA actuator of claim 1 or claim 2, wherein the plurality of SMA wire sections are connected to form at least two separate electrical paths which are electrically connected in parallel.

4. The SMA actuator of claim 2 or claim 3, wherein each electrical path comprises SMA wire sections which form a continuous SMA wire.

5. The SMA actuator of any one of claims 2 to 4, wherein the number of SMA wire sections which are electrically connected in series and the number of SMA wire sections which are electrically connected in parallel is selected to generate a predetermined resistance.

6. The SMA actuator of any preceding claim, wherein at least one parameter of the plurality of SMA wire sections is selected so that when the plurality of SMA wire sections contract a minimum force in the direction of movement of the moveable element is generated and the moveable element moves a minimum distance.

7 The SMA actuator of claim 6, wherein the at least one parameter is selected from the group comprising the acute angle between the axis of each of the plurality of SMA wire sections, the diameter of each of the plurality of SMA wire sections, the length of each of the plurality of SMA wire sections and the number of SMA wire sections.

8. The SMA actuator of any preceding claim, wherein each of the plurality of SMA wire sections is less than 3mm in length, preferably between 1mm and 2.5mm in length.

9. The SMA actuator of any preceding claim, wherein the acute angle is less than 70 degrees.

10. The SMA actuator of any preceding claim, wherein each of the plurality of SMA wire sections is at the same acute angle.

11. The SMA actuator of any preceding claim, wherein there are between 12 and 30 SMA wire sections.

12. The SMA actuator of any preceding claim, wherein one end of each of the plurality of SMA wire sections is coupled to one edge of the moveable element and the opposed end of each of the plurality of SMA wire section is coupled to an adjacent edge of the static element.

13. The SMA actuator of claim 12, wherein the adjacent edge of the static element comprises a recess having an angled slope and each of the plurality of SMA wire sections extends along the angled slope.

14. The SMA actuator of any one of claims 1 to 11, wherein the moveable element is located between first and second portions of the static element and the plurality of SMA wire sections comprise a plurality of pairs of SMA wires with a first SMA wire in each pair having one end coupled to the first portion of the static element and the opposed end coupled to an adjacent edge of the moveable element and a second SMA wire in each pair having one end coupled to the second portion of the static element and the opposed end coupled to an adjacent edge of the moveable element.

15. The SMA actuator of claim 13, wherein each of the first and second portions comprises a recess having an angled slope and each of the plurality of SMA wire sections extends along the angled slope of the respective recess.

16. The SMA actuator of any one of claims 11 to 15, wherein the moveable element comprises an angled flange to which an end of each SMA wire section is attached.

17. The SMA actuator of any preceding claim, wherein at least one of the plurality of SMA wires sections is coupled to at least one of the static element and the moveable element using a crimp connector.

18. The SMA actuator of claim 17, wherein the crimp connector holds a plurality of SMA wires sections.

19. The SMA actuator of any preceding claim, wherein at least one of the plurality of SMA wires sections is coupled to at least one of the static element and the moveable element using a protruding element around which the SMA wire section is looped.

20. A haptic assembly comprising a touchable component and the SMA actuator of any one of claims 1 to 19, 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.

21. A latch comprising the SMA actuator of any one of claims 1 to 19.