Patent ID: 7789624
Filing Date: 2010-09-07
Classification: F03D,F05B,Y02E

Abstract:
1. A passive pitchable device for wind turbines comprising: a camshaft having a plurality of engraved cam grooves; said cam grooves are like a half sine wave like groove; a cylindrical shell for supporting a blade assembly; said blade assembly and said cylindrical shell are fastened together by screws; an axial compression spring, which is contained within said cylindrical shell; to retrieve the blade to its initial feathering position when the blade is not rotating; a plurality of balls that roll along said cam grooves, and convert the axial displacement to rotation or pitch angle; wherein said cam grooves determine a smart blade angle with respect to the resultant wind speed vector; wherein said axial compression spring returns said smart blade to its initial feathering position when said smart blade is not rotating; and wherein the passive pitchable device effectively achieves easy-starting from a stationary state, optimum aerodynamic efficiency at low and design wind speeds and controlled performance at high wind speeds.