| 摘要 |
A shaft ( 40 ) subject to torque about its axis (A-A) has an axial bore ( 42 ). A region ( 44 ) of the shaft ( 40 ) has a stored magnetisation, the region ( 44 ) being permanently magnetised with circumferential magnetisation about the axis (A-A) or an annulus of longitudinal magnetisation which is preferred. The stored magnetisation emanates a torque-dependent field into the bore ( 42 ). A magnetic field sensor arrangement ( 50 ) is positioned in the bore to produce a torque-dependent signal. The disclosure discusses the relationship between the radial depth (t<SUB>m</SUB>) of the permanent magnetisation in region ( 44 ) relative to the shaft wall thickness (t). Magnetic sensor placements include axial ( 52, 54 ) or offset arrangements of pairs of sensors ( 52 a,b, 54, b). Dependent on the nature of the field to be sensed, sensors ( 5 ) may be oriented axially, radially or tagentially with respect to the axis (A-A). |
