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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 mova

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 movable magnet in response to the excitation signal induces another electromotive force in the two-wire circuit when it propagates to the second magnet.

대표청구항 ▼

[ What is claimed is:] [1.] A magnetostrictive position measurement apparatus comprising:a circuit including a magnetostrictive wire having first and second opposed ends, the circuit transmitting an electrical excitation pulse and detecting a return signal indicative of the position of a first magne

[ What is claimed is:] [1.] A magnetostrictive position measurement apparatus comprising:a circuit including a magnetostrictive wire having first and second opposed ends, the circuit transmitting an electrical excitation pulse and detecting a return signal indicative of the position of a first magnet along the magnetostrictive wire on the basis of the time delay between the detection of the return signal relative to the transmission of the electrical excitation pulse;the first magnet displaceable relative to the magnetostrictive wire, the first magnet interacting with the electrical excitation pulse and generating first and second oppositely propagating torsional waves in the magnetostrictive wire; andmeans for reflecting the second torsional wave from the second end of the magnetostrictive wire to the first magnet wherein the magnetic field of the first magnet interacts with the second torsional wave to induce an electrical current in the magnetostrictive wire, the electrical current acting as the return signal.