Horizontal axis wind generator having adaptive cyclic pitch control

Abstract

Cyclic pitch variation of the rotor blades of a horizontal axis wind energy conversion machine permit its operation at substantially design rotor speed and rotor torque over a range of wind speeds, by heading the rotor progressively out of the wind through a range from approximately 20.degree. for light winds to a near 90.degree. setting for gales, at which the power output is interrupted to permit the rotor to idle. Changes in wind direction will cause the rotor to follow the wind even though so headed out of it. By allowing the blades substantial freedom to adapt their pitch to side winds, the present construction allows rapid rates of yaw into a shifting wind, such as may destroy conventional rotors by the attendant gyroscopic forces. Further, by actively controlling their pitch, aerodynamic forces exerted by the cyclic pitch change blades substantially balance out the gyroscopic forces attendant to yaw. The preferred rotor uses only two blades mounted on a common shaft which oscillates cyclically in the hub. Since cyclic variation of blade pitch establishes a cyclic pitch center of rotation offset from the rotor axis; by moving this offset the rotor is caused to yaw at a controlled rate in a desired sense.

Dependencies are inferred from the claim text.