Patent ID: 7665569
Filing Date: 2010-02-23
Classification: B62D

Abstract:
1. A power steering system comprising: a hydraulic power cylinder having a first hydraulic chamber and a second hydraulic chamber, for assisting a steering force of a steering mechanism adapted to be linked to steered road wheels; a first oil passage connected to the first hydraulic chamber; a second oil passage connected to the second hydraulic chamber; a reversible pump having a pair of outlets each connected to respective one of the first and second oil passages, for discharging operating oil and for providing oil pressure to the hydraulic power cylinder; a motor connected to the reversible pump and rotating the reversible pump in normal and reverse directions; a steering load detection unit detecting a steering load of a steering wheel for steering of the steered road wheels; a motor control unit outputting a control signal to the motor to bring an actual oil pressure generated by the reversible pump closer to a desired oil pressure determined based on the detected steering load; and a discharge amount per rotation of the reversible pump being smaller than or equal to 5 cc, wherein a maximum motor torque required to drive the reversible pump is less than a motor torque at a maximum output of the motor.