Electrohydraulic steering system for automobile with separate steering circuits for steer-by-wire and servo-assisted mechanical steering modes

摘要

The electrohydraulic steering system (10) has 2 separate steering circuits (64,65), the first steering circuit having an electronic steering control (18) for controlling an electrohydraulic regulating valve in dependence on the detected rotation of the steering wheel (11), which is used for mechanical operation of a hydrostatic steering valve (16) in the second steering circuit. Both steering circuits employ the same pump (49), coupled to the hydrostatic steering valve via a switching valve (71) controlled by the electronic steering control, which also controls an electric servo motor for servo-assisted emergency steering.