Non-contacting sensor for measuring relative displacement between two rotating shafts

A torque sensor for attachment between a first and second steering column shaft of a vehicle, the first shaft connected to a steering wheel and the second shaft connected to a vehicle steering linkage, a torsion spring bar connected between the first and second shafts allowing rotational movement between the first and second shafts, comprising:

• (a) a housing having a first and second aperture at each end thereof, the first shaft extending through the first aperture into the housing and the second shaft extending through the second aperture into the housing, the shafts each having an end that is located adjacent each other in the housing such that the shafts are co-axial to each other;
• (b) a planetary gear assembly connected to the first and second shafts, the planetary gear assembly having a first ring gear connected to the first shaft, a second ring gear connected to the housing, a first planet gear engaged between the sun gear and the first ring gear and a second planet gear engaged between the sun gear and the second ring gear, the first and second shafts when rotating in a non-coaxial manner causing the first ring gear to change an angular position relative to the second ring gear
• (c) a variable magnetic field generator connected to the first ring gear, the variable magnetic field generator moving proportional to the relative angular change between the first ring gear and the second ring gear;
• and
• (d) a magnetic field sensor located adjacent the variable magnetic field generator and connected to the housing, the magnetic field sensor generating an electrical signal in response to rotational movement of the variable magnetic field generator, the electrical signal being proportional to the difference in angular positions of the first and second shafts which is indicative of the amount of torque being applied to the first and second shafts.