Consideration of control edge geometry to power steering characteristics

The control edge geometry of a hydraulic pinion/rack power steering valve is studied and the valve characteristics modelled. Non-facet and two-facet control edges have been studied and the geometry data of the later are from a commercial product. The characteristics from simulation and experiment of a test-rig show the steering feeling, and the two-facet control edge valve was designed for safer and friendly steering manipulation. The hydraulic pump pressure, determined as a function of the steering twist angle, is incorporated in the steering control valve characteristics. A modification at the control edge geometry is proposed, and its characteristics show that there is large room available at the control edge design to improve the steering feeling and safe manipulation.