PROCEDE ET MECANISME DE COMMANDE DU FLUX VOLUMIQUE D'UN SYSTEME HYDRAULIQUE DE DIRECTION ASSISTEE DE VEHICULES AUTOMOBILES

摘要

A apparatus for use with an open center steering valve (3) of a hydraulic power-assisted steering unit of a motor vehicle. The apparatus comprises an electric motor operated pump (5) and a hydraulic accumulator (7) for storing a pressurized quantity of hydraulic fluid. The hydraulic accumulator (7) is hydraulically connected to the pump (5). The pump (5) supplies the pressurized hydraulic fluid to the hydraulic accumulator (7). The apparatus further comprises a valve arrangement (10) for controlling hydraulic fluid flow from the hydraulic accumulator (7). The valve arrangement (10) has a riser (25), a slide valve (19), a valve seat (21), and an electromagnet. The riser (25) is hydraulically connected to the pump (5). The valve seat (21) has an opening which hydraulically connects the riser (25) and the hydraulic accumulator (7). The slide valve (19) is located within the electromagnet of the valve arrangement (10) and is movable by the electromagnet from a position blocking the valve seat opening and preventing hydraulic fluid flow from the accumulator (7) to the riser to a position clearing the valve seat opening and allowing hydraulic fluid flow from the accumulator (7) to the riser (25). The apparatus further comprises an electronic control unit (6) for controlling the electromagnet and the movement of the slide valve (19).