Noncontact Torque Sensor Using Magnetic Heads

A noncontact torque sensor based on magnetic heads positioned at 45° to the shaft was studied. Plotting the static torque detection characteristics for various ribbon-head spacings showed that for spacings of from 0.5 to 0.7 mm, the characteristics do not change much. The zero-point variations for spacings from 0.2 to 0.7 mm were under 0.7 mV. A driving frequency ¿/2¿ = 312 kHz was employed to minimize the effect of the ferromagnetic shaft. When a large shaft is used making the sensor configuration proportionately larger may result in a spacing of several mm.