US 12,169,148 B2
Magnetic field differential torque sensor
Till-Jonas Ostermann, Germany (DE); and Alexander Latham, Harvard, MA (US)
Assigned to Allegro MicroSystems, LLC, Manchester, NH (US)
Filed by Allegro MicroSystems, LLC, Manchester, NH (US)
Filed on Feb. 16, 2022, as Appl. No. 17/651,265.
Prior Publication US 2023/0258515 A1, Aug. 17, 2023
Int. Cl. G01L 3/10 (2006.01); G01L 5/22 (2006.01)
CPC G01L 3/101 (2013.01) [G01L 3/104 (2013.01); G01L 5/221 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A differential magnetic field torque sensor, the sensor comprising:
a first multipole magnet assembly having a plurality of magnetic pole pairs and configured for coupling to a first rotatable shaft;
a second multipole magnet assembly having a plurality of magnetic pole pairs and configured for coupling to a second rotatable shaft, wherein the first rotatable shaft is coupled to the second rotatable shaft by an elastic element;
a first differential magnetic field angular position sensor positioned proximate to the first multipole magnet assembly and configured to produce an angular position of the first multipole magnet assembly;
a second differential magnetic field angular position sensor positioned proximate to the second multipole magnet assembly and configured to produce an angular position of the second multipole magnet assembly; and
a processing unit operative to receive an angular position from each of the first and second differential magnetic field angular position sensors and determine a difference between the angular positions, wherein the difference corresponds to an angle, and wherein the processing unit is operative to calculate, based on the angle, a torque applied to the first or second rotatable shaft;
wherein each of the first and second differential magnetic field angular position sensors includes:
(i) a first array of magnetic field sensing elements;
(ii) a second array of magnetic field sensing elements, wherein the first array of magnetic field sensing elements is spaced a distance from the second array of magnetic field sensing elements, wherein the first and second arrays of magnetic field sensing elements each have at least first and second axes of maximum sensitivity, wherein the first axis of maximum sensitivity is orthogonal to the second axis of maximum sensitivity; and
(iii) an angular position module operative to determine the angular positions of the first and second multipole magnet assemblies assembly from differential signals from the first and second arrays of magnetic field sensing elements;
wherein, for the first differential magnetic field angular position sensor, the distance the first array of magnetic field sensing elements is spaced from the second array of magnetic field sensing elements is configured to match a pitch of adjacent magnetic pole pairs of the first multipole magnet assembly; and
wherein, for the second differential magnetic field angular position sensor, the distance the first array of magnetic field sensing elements is spaced from the second array of magnetic field sensing elements is configured to match a pitch of adjacent magnetic pole pairs of the second multipole magnet assembly.