Fluid pressure driven rotary actuator and method of operating the same

Abstract

A hydraulic rotary actuator assembly includes a rotatable drive assembly disposed about and rotatable about a longitudinal axis of the actuator and a stator assembly disposed about the rotatable drive assembly. The rotatable drive assembly includes an output shaft having a coupling end for rotatably engaging a workpiece, and a rotor disposed concentrically about the longitudinal axis and rotatable to drive rotation of the output shaft. The rotor has an outside radial surface that includes at least one radially protruding flange or rotor vane. The stator assembly is disposed concentrically about and generally radially spaced from the rotor and has at least one radially movable stator vane that is sealingly engageable with the outside radial surface of the rotor. Sealing engagement between the stator vane and the outside concentric surface forms at least a first pressure cavity and a second pressure cavity, such that first and second pressure cavities are sealingly bounded by at least the rotor vane the and stator vane. Further, a fluid pressure system is provided in fluid communication with the first and second pressure cavities to produce a differential pressure acting on one side of the rotor vane, thereby rotatably moving the output shaft assembly. Each of the stator vanes is radially movable responsive to a variable control element such as a variable pressure cavity. The variable control element is operable by a stator vane control system (e.g, a system including one or more solenoid valves and pressure fluid accumulator) to change the radial position of the vanes relative to the stator and in synchronization with the rotation of the rotor. Accordingly, the rotor assembly of the actuator is continuously movable or rotatable in one direction relative to the stator assembly beyond 360 degrees and without significant pause or change of direction.