摘要 |
A hydraulic reaction force apparatus for a power steering system has a pump, a power cylinder, a control valve, a first variable orifice, a hydraulic reaction force chamber, and a spool valve. The spool valve has a supply port connected to the pump, a reaction port connected to the hydraulic reaction force chamber, a tank port connected to a tank and a second variable orifice controlled by a spool in the spool valve. The opening of the second variable orifice is changed by a displacement of the spool caused by the pressure difference between upstream and downstream pressures of the first variable orifice, thereby connecting the reaction port to the supply port and the tank port and controlling the magnitude of the hydraulic reaction force. |