Patent ID: 6179082
Filing Date: 2001-01-30
Classification: B62D

Abstract:
A hydraulic steering apparatus for an automatic traveling vehicle comprising:means for inputting a target steering angle;a pilot valve, having a neutral position and left and right steering positions, for outputting pressurized oil, from a first oil pressure source, after being switched from said neutral position to one of said left and right steering positions;a main steering valve having a neutral position and left and right steering positions for receiving pressurized oil from said pilot valve and for outputting pressurized oil, from a second oil pressure source, after being switched from said neutral position to one of said left and right steering positions;a plurality of hydraulic actuators for receiving pressurized oil from said main steering valve to produce an actual steering angle in said automatic traveling vehicle;means for outputting an excitation current, based upon a deviation between said target steering angle and said actual steering angle; andan electromagnetic variable pressure reducing valve for switching pressurized oil from said pilot valve to said main steering valve based upon said excitation current,wherein said pilot valve comprises:a first sleeve for receiving said target steering angle;a second sleeve for receiving said actual steering angle;a first spring for applying a spring force to urge said first sleeve and said second sleeve toward said neutral position based on a relative position of said first sleeve and said second sleeve to said left and right steering positions;means for detecting said target steering angle from said first sleeve;means for detecting said actual steering angle from said second sleeve; andwherein said actual steering angle is produced by following said target steering angle.