| 摘要 |
A power steering system includes a hydraulic pump and a hydraulic steering mechanism. A flow control orifice passes fluid from the pump to the steering mechanism and generates a hydraulic control signal proportional to the fluid flow rate therethrough. A flow control valve is connected between the pump to bypass fluid away from the steering mechanism in response to the hydraulic control signal. A solenoid operated valve is located in a pilot fluid circuit between the pump and the flow control orifice to vary the hydraulic control signal in response to an electrical control signal. The electrical control signal is a pulse width modulated signal having a duty cycle proportional to vehicle speed. Maximum power assist occurs when vehicle speed is below a predetermined value and decreases with increasing vehicle speed above the predetermined value. |
