Patent ID: 8818635
Filing Date: 2014-08-26
Classification: B62D

Abstract:
1. An electric power assisted steering apparatus for a vehicle, the apparatus comprising: a steering mechanism, which operatively connects a steering wheel to road wheels of the vehicle; an electric motor operatively connected to said steering mechanism; a torque sensing means adapted to produce a first output signal indicative of the torque carried by a portion of said steering mechanism; a vehicle speed sensing means for producing a second output signal indicative of the speed of said vehicle; a signal processing means adapted to receive said first output signal and said second output signal and to produce a torque demand signal representative of the torque to be applied to said steering mechanism by said motor; a motor drive stage adapted to provide a drive current to said motor responsive to said torque demand signal; and a torque limiter arranged to limit at least one of the torque and the maximum rate of increase of the torque following a restart of the apparatus, the limit and maximum rate of increase of the torque being determined at least in part by information indicative of a state of the system prior to the restart, and, in the event that the information indicates that the system shutdown normally while a drive current was not being provided to the motor prior to restart, the at least one of the limit and the maximum rate of increase of the torque applied is different than that applied in the event that the information indicates that the system shutdown abnormally while a drive current was being provided to the motor prior to the restart.