Electric power assisted steering system

• Main Author: Farrelly, James Owen Patrick
• Format: Patent
• Language: English
• Published: 03.07.2018
• Subjects: LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS; MOTOR VEHICLES; PERFORMING OPERATIONS; TRAILERS; TRANSPORTING

An electric power assisted steering apparatus comprising a combined angular position and torque sensor assembly comprising an upper column shaft that in use is operatively connected to a steering wheel of the vehicle, a lower column shaft that in use is operatively connected to the road wheels of the vehicle, a torsion bar that interconnects the upper column shaft and the lower column shaft, a first and a second torque signal generating means that each generate a first torque signal based on angular deflection of the torsion bar, an absolute position signal generating means that in use produces an absolute upper column position signal indicative of the angular position of the upper column shaft, an electric motor that is connected to the lower column shaft of the torque sensor assembly, and a motor position sensor carried by the motor that provides a motor position signal dependent on the angular position of the motor rotor. The apparatus further comprises a virtual torque signal generating means that in use is adapted to determine a third torque signal from a combination of the motor position signal and the absolute angular position signal produced by the processing means.