(DISC) MAGNETIC TORQUE SENSING WITH SEGMENTS

A torque transducer system comprises a disc through which torque is transmitted in a radial direction and which has a magnetised annular region which emanates a torque-dependent magnetic field. A non-contacting magnetic field sensor detects the emanated field. The annular region comprises segments by means of which a pulsed magnetic field is emanated as the disc rotates. The segments may be magnetically unipolar and spatially separated or of alternate polarity. They may be integral with the disc of or material applied to the disc that is magnetised or that segments an underlying magnetisation in the disc. The preferred direction of magnetisation is radial and the effect of the orientation of a sensor with respect to the radial field is discussed. One sensor arrangement comprises a pair of sensors oriented at an angle to one another with reference to the radial field. The teachings of the invention can be applied to the segmentation of an integral transducer region of a torque-transmitting shaft, the region having an annulus of axially-directed remanent magnetization.