Patent ID: 6311799
Filing Date: 2001-11-06
Classification: B62D

Abstract:
A power steering apparatus, comprising:steering direction detection mechanism that senses a direction of steering operation of a steering mechanism;steering angular speed detection mechanism that senses a steering angular speed when the steering mechanism is operated; andmotor control circuit that determines a rotation speed of an electric motor in accordance with the steering angular speed sensed by the steering angular speed detection mechanism, and controls driving of the electric motor on the basis of an output of the steering direction detection mechanism so that, with respect to a given steering angular speed, the motor rotation speed is set at a lower value when the steering mechanism is operated toward a steering angle midpoint than when the steering mechanism is operated away from the steering angle midpoint,wherein said motor drives a pump for generating hydraulic pressure that generates a steering assist force to be applied to the steering mechanism, andwherein the motor control circuit determines the motor rotation speed with respect to the steering angular speed sensed by the steering angular speed detection mechanism in accordance with a first characteristic line which defines a linear relationship between the steering angular speed and the motor rotation speed for the steering operation away from the steering angle midpoint, and in accordance with a second characteristic line which defines a linear relationship between the steering angular speed and the motor rotation speed for the steering operation toward the steering angle midpoint, the second characteristic line defining the relationship such that the steering angular speed with respect to the motor rotation speed of the second characteristic line that is greater than the steering angular speed with respect to the motor rotation speed of the first characteristic line.