Abstract
Characteristics of a magnetostrictive torque sensor were studied in the excitaion current range from 10 to 1000 mA and the exciting frequency range from 1 k to 100 kHz. Ni-Cr-Mo steel (SNCM439 in JIS code) of ferromagnetic material was used as an experimental shaft because of high mechanical strength in the applied torque range from -1500 to 1500 Nm.
The sensor sensitivity was markedly enhanced and the hysteresis and the deviation of offset along the shaft circumference were reduced as the excitation current was increased. Good sensor outputs have been obtained in the high excitation current range over 200 mA.
A new memory phenomenon, which seems to be magnetic domain change induced with stress due to torque, has been found in the low excitation current range.
