A Single Transducer for Non-Contact Measurement of the Power, Torque and Speed of a Rotating Shaft

Simple constructional modifications extend the capability of polarized ring torque transducers, when applied to rotating shafts, to include the measurement of power and speed. Gear-like teeth on thin, high permeability rings affixed to the polar regions of the magnetoelastically active ring spatially modulate the magnetic field arising with the torque. Speed is found from the frequency of the ac component of the field sensor signal while torque is found from its amplitude. Drift in quiescent outputs of low cost Hall effect sensors have no effect on these ac signal features. Signals proportional to transmitted power are generated in sensing coils by shaft rotation.