| 摘要 |
<p>An improved power steering apparatus includes a pressure modulation assembly which modulates the fluid pressure transmitted from a power steering control valve to a power steering motor. The modulation assembly varies the fluid pressure output from the steering control valve as a direct function of vehicle speed. This results in relatively easy steering for parking and low speed maneuvers and a firmer feel for maneuvers at higher speeds. The pressure modulation assembly is connected in series fluid communication with and between the power steering control valve and the power steering motor and includes a pair of pressure modulation valves. Fluid for actuating the power steering motor flows from the power steering control valve through the pressure modulation valves to the power steering motor. The pressure modulation valves are biased closed by the output pressure from an auxiliary pump which is driven at a speed which varies as a function of vehicle speed. Thus, the pressure of the fluid delivered to the power steering motor is reduced by the pressure modulation valve to an extent determined by the magnitude of the biasing force derived from the speed dependent auxiliary pump.</p> |
