New torque sensors using amorphous star-shaped cores

New non-contact type accurate torque sensors detecting the twist angle of a shaft independent of its rotation speed are presented using one pair or twin pairs of amorphous star-shaped cores. Each core is combined with a voltage-output type multivibrator (or multivibrator bridge), which forms a magnet-field sensor. In each star-shaped core, n number of amorphous branch cores are serially connected with each other and face to a n-pole ring magnet fixed to the shaft. The star-shaped cores have three advantageous functions: (i) averaging the irregular distribution of magnetization strength of the pole, (ii) cancellation of external disturbance fields, and (iii) cancellation of deflection of rotation axis of the shaft. It is possible to detect a twisted angle as small as 0.002° for static shafts and 0.01° for rotating shafts.