Patent attributes
An improved torque sensing arrangement includes a magnetoelastic ring on a rotatable shaft, along with two or more magnetic field sensors. The ring has at least two magnetic bands magnetized in opposite directions to produce at least two magnetic fields. Alternatively, the rotatable shaft could be magnetized into bands, eliminating the need for a magnetoelastic ring. The magnetic field sensors are positioned next to, but not contacting, the bands, and can be used to measure the field strength, which can be converted to torque. The sensors are preferably positioned to either side of the peak axial magnetic field strength areas of the bands, one offset from the center of one band in a first direction and the other offset from the center of the other band in a second direction opposite the first direction, thereby limiting the average change in the reading when the fields move under the shaft.
