Torque sensor for a power assist steering system

Abstract

A torque sensor is presented for use in a power assist steering system for sensing the applied steering torque between an input shaft and an output shaft and wherein the shafts are coaxially aligned and rotatable relative to each other about a common axis. The sensor includes a rotary input transformer having a stationary primary winding and a rotary secondary winding. A rotary transmitter is driven by the input shaft for rotation therewith about the common axis. The transmitter carries a coil set including a plurality of series connected coils arranged in an annular array about the axis on an axially directed face of the transmitter. All of the coils are wound in the same direction and are electrically connected to the secondary winding for receiving an input signal therefrom. A rotary receiver is axially spaced from the transmitter and is driven by the output shaft for rotation therewith about the common axis. The receiver has an axially directed face extending toward the transmitter face and carries first and second coil sets. Each coil set includes a plurality of series connected coils with each coil being wound in the same direction. First and second rotary output transformers are provided having first and second primary windings respectively electrically connected to the first and second receiver coil sets and driven by the output shaft for rotation about the common axis. The output transformers include first and second stationary windings.