Patent ID: 6223852
Filing Date: 2001-05-01
Classification: B62D

Abstract:
An electric power steering apparatus for a vehicle, comprising:a battery;an electric motor for applying a steering assist force to a steering system of a vehicle;a control unit for generating a motor control signal on the basis of at least a steering torque applied to the steering system;a motor drive unit for driving said electric motor on the basis of said motor control signal;an ignition sensor for detecting an operating condition of an ignition switch of the vehicle;an engine running-state sensor for detecting a running state of an engine of the vehicle and generating an engine running-state signal corresponding to the detected running state of the engine; anda protection circuit for said battery including a switching unit arranged to interrupt operation of said electric motor when a signal indicative of an ignition off state of said ignition switch is supplied from said ignition sensor and the engine running-state signal supplied from said engine running-state sensor falls below a predetermined value;wherein the protection circuit prevents the electric motor from being stopped during an off failure where the ignition switch off state signal is erroneously output from the ignition sensor and the engine is still running above a predetermined value, but the protection circuit protects the battery from power drain and stops possible operation of the electric motor when the ignition switch off state signal is output from the ignition sensor and the engine is stopped or running below the predetermined value.