Pickupless magnetostrictive position measurement apparatus
US5998991A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 10, 1997 |
| Grant date | Dec 7, 1999 |
| Priority date | — |
| Expiry date | Nov 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/72
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for determining the position of a movable object along a magnetostrictive wire having first and second opposed ends. A first electrical excitation pulse is applied to a two-wire circuit including the magnetostrictive wire and propagates along the wire to the position of a movable magnet surrounding the wire. The magnet generates oppositely directed first and second torsional waves in the wire. One torsional wave propagates along the wire to a reflective termination at the second end of the wire and is reflected back toward the magnet where it interacts with the magnetic field of the magnet to induce a return electrical pulse in the two-wire circuit. The position of the magnet along the wire is determined from the time differential between the first and second electrical pulses in the two-wire circuit. In another embodiment, a second magnet is mounted in a fixed position about the wire and generates oppositely directed third and fourth torsional waves in response to the first excitation signal, one of which propagates along the wire toward the first magnet which induces an electromagnetic force in the two-wire circuit. A torsional wave generated by the first m…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.