Aircraft engine unducted fan blade pitch control system

摘要

An electric motor driven blade pitch varying system for the fan blades of an unducted fan type aircraft gas turbine engine utilizes permanent magnet alternating current motors located in the oil sump region of the engine. An alternator driven by the engine generates unregulated variable frequency, variable amplitude power which is rectified and placed on a DC bus. Controlled inverters convert the DC power on the bus to appropriate AC power for the motors. The system incorporates redundancy without significant weight penalty by providing alternators and motors dividing into two independent operating sections on common shafts. Separate electronic circuits are provided to supply power for each sectionalized motor or to rectify power from each alternator section. A common power bus may be used to couple the multiple motors and alternators. The common bus may alternatively receive power from tbe aircraft 400 Hz system or from on-board batteries.