Power assisted steering system for a motor vehicle and control means therefor

Claim 1

A power assisted steering system for a motor vehicle having at least one steerable road wheel, the system comprising: a steering shaft manually rotatable by a driver of the vehicle; a steering mechanism to convert rotation of the steering shaft into steering movement of the or each steerable road wheel; an electric motor having a rotor and a wound stator encircling the rotator; a torque sensor to provide a signal indicative of the torque difference between the torque applied to the steering shaft by a driver of the vehicle rotating the steering shaft and the assistance torque applied by the electric motor to the steering shaft and control means to supply a control signal to the electric motor in response to the signal received from the torque sensor wherein the electric motor is a brushless electric motor having a number of permanent magnets connected to part of the steering shaft for rotation therewith to form the rotor, each of the permanent magnets connected to a part of the steering shaft by being press fitted into a respective recess in the steering shaft.