Rotary servovalve for power-assisted steering system

摘要

A rotary servovalve includes a valve sleeve formed with a supply port for connection to a source of fluid under pressure and distribution ports respectively for connection to opposite fluid chambers of a hydraulic power cylinder, the valve sleeve being formed at the inner periphery thereof with circumferentially spaced sleeve channels respectively in open communication with the supply and distribution ports, and a valve rotor coupled with the valve sleeve for relative rotation thereto, the valve rotor being formed thereon with circumferentially spaced control lands which are arranged to correspond with the sleeve channels when the servovalve is in a neutral position. The control lands corresponding with the sleeve channels in open communication with the distribution ports are each formed larger in width than the corresponding sleeve channel and smaller in height than the control land corresponding with the sleeve channel in open communication with the supply port to define a predetermined clearance for restricting the flow of fluid discharged from and supplied into the distribution ports when the servovalve is in the neutral position.