Method and device for actuating shape memory alloy member
US4747887A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 13, 1987 |
| Grant date | May 31, 1988 |
| Priority date | — |
| Expiry date | Apr 13, 2007 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22F1/006
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method for actuating a member made of shape memory alloy, including stressing the shape memory alloy member so that its Ms point becomes positioned between its As point and its Af point, and applying a pulsed supply of electricity to it to heat it up is disclosed. The voltage and the duty factor d of the pulsed supply of electricity ensure that the relations .theta.ha greater than -.theta.ca and "d" less than or equal to .theta..sub.cc /(.theta.cc -.theta.hb ) are satisfied, where .theta..sub.ha is the heating speed of the shape memory alloy member in the region below its As point, .theta.hb is the heating speed of the shape memory alloy member in the region between its As point and its Af point, .theta..sub.cc is the cooling speed of the shape memory alloy member in the region above its Ms point, and .theta.ca is the cooling speed of the shape memory alloy member in the region below its Mf point. Thereby, the shape memory alloy member is heated in an even, smooth, and controlled fashion for its actuation, so that there is substantially no risk of overheating of any of its parts during actuation, because large temperature differentials are not produced in the member. Thus, the se…
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