Patent ID: 7664583
Filing Date: 2010-02-16
Classification: B62D

Abstract:
1. An electric power assisted steering apparatus for a vehicle having a steering wheel and road wheels, comprising: a steering mechanism, which operatively connects said steering wheel to said road wheels of the vehicle; an electric motor operatively connected to said steering mechanism; a torque sensor adapted to produce a first output signal indicative of the torque carried by a portion of said steering mechanism; a vehicle speed sensor for producing a second output signal indicative of the speed of said vehicle; a signal processing unit adapted to receive said first signal and second signal and to produce a torque demand signal representative of a torque to be applied to said steering mechanism by said motor; and a motor drive stage adapted to provide a drive current to said motor responsive to said torque demand signal, wherein said apparatus includes torque limiting device, arranged to limit the magnitude of said torque to be applied to said steering mechanism to a maximum of a value that increases in time from a first value to a second value at a rate that is dependent on said second signal.