MAGNETIC DIFFERENTIAL TORQUE SENSOR

A new torque sensor structure is presented. The basic idea is a simple torque sensor with a variable magnetic circuit excited by an axially magnetized permanent magnet ring. The circuit is constituted by iron t oothed rings, whose teeth relative position changes whenever an applie d torque twistes the rotating shaft. A Hall probe measures the inducti on in an airgap where the induction is uniform. The new structure is a n association of two previous ones, thus creating a differential syste m with the related advantages: diminution of thermal drifts, zero mean value for the signal. The new magnetic circuit is studied by calculat ing equivalent reluctances through energy calculations and by using el ectrical analogies.