Electric power steering system

摘要

Provided is an electric power steering system that prevents the oscillation of the steering wheel at each steering stroke end. If the steering stroke end flag Fse is 1 or if the determination result is Yes in step S8, the EPS-ECU (21) determines if the right steering flag (Fdrc) is 1 in step S10. If the determination result is Yes, it is then determined if the steering torque difference base value (Dtsb) is positive in step S11. If the determination result of step S11 is Yes, the EPS-ECU (21) uses the steering torque difference base value (Dtsb) as the steering torque difference (Dts) in step S12. If the determination result is No, the steering torque difference (Dts) is given by a value 0 in step S13, and the control process is concluded.

主权项

1. An electric power steering system, comprising:
an electric steering assist motor that applies an assist force to a steering mechanism; a steering angle detector that detects a steering angle of a steering wheel; a target steering torque setting unit that sets a target steering torque of the steering wheel according to a detection result of the steering angle detecting means detector; an actual steering torque detector that detects an actual steering torque applied to the steering wheel by a vehicle operator; a steering torque difference computing unit that computes a difference between the target steering torque and the actual steering torque as a steering torque difference; an effective steering torque difference determination unit that determines and produces an effective steering torque difference, such that the effective steering torque difference is given as zero when the actual steering torque is greater than the target steering torque in a steering angle advancing direction by more than a prescribed value and otherwise the effective steering torque difference is given as the steering torque difference computed by the steering torque difference computing unit; a target drive current setting unit that sets a target drive current according to the effective steering torque difference; and a motor drive circuit that drives the steering assist motor according to the target drive current.