Patent ID: 6772646
Filing Date: 2004-08-10
Classification: G01L

Abstract:
A differential capacitive torque sensor for a continuously rotating shaft where the shaft is split into first and second halves by a buried torsion bar comprising:a dielectric disk having a plurality of spokes mounted for rotation with the first half of said shaft; a pair of first and second apertured conductive disks forming a cage for said dielectric disk and mounted for rotation with the second half of said shaft, said cage shielding portions of said spokes of said dielectric disk in proportion to applied shaft torque; a pair of concentric capacitor plate rings lying in a common plane, one ring having a greater diameter than the other ring encircling said first half and juxtaposed with said first apertured conductive disk; an opposed capacitor plate, encircling said second half and juxtaposed with said second apertured conductive disk; each apertured conductive disk including apertures arranged in a pair of concentric rings that match the first and second concentric plate rings, which encircle said first half, said apertures alternating with solid conductive portions around a circle, said concentric rings being offset from one another so that at least part of the solid portion of one ring matches the aperture of the other to provide differential capacitances; and electrical bridge means for comparing the capacitances formed between said pair of concentric rings and said opposed capacitor plate for determining said applied shaft torque.