Strain detector with magnetostrictive elements
US4986137A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1989 |
| Grant date | Jan 22, 1991 |
| Priority date | — |
| Expiry date | Dec 1, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L3/103
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A strain detector for detecting a strain developed in a shaft applied with a torque comprises strain-sensitive magnetostrictive elements attached to the shaft in two groups in a chevron pattern. A pair of annular detection coils are wound around a bobbin to surround respective one of the groups of magnetostrictive elements. Two annular yokes made of a soft magnetic material of high permeability are disposed around respective coils across radial gaps. A hollow cylindrical shield of non-magnetic material with a high electrical conductivity is disposed around the two yokes across radial gaps. The magnetostrictive elements may be made of a nickel-iron alloy of 45 to 55% Ni-Fe. The yokes may be made of a nickel-iron alloy of about 80% Ni-Fe or alternatively, of a 6.5% Si-Fe steel. The detector may comprise a second magnetic shield disposed around the first shield of non-magnetic material with a high electrical conductivity. The second shield may be made of the same magnetic material as the yokes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.