VERTICAL AXIS DRAG TYPE WINDMILL

PROBLEM TO BE SOLVED: To provide a small-sized windmill of a vertical axis drag type, which efficiently rotates stably from starting to operation with strong winds in order to offer service, installed in an urban district, in which such an arrangement is introduced that starting is made at a low wind speed, a good power generating efficiency is obtained in rotating, and the windmill and generator are protected by controlling the rotating speed in operating with strong winds. SOLUTION: The windmill is equipped with a plurality of blades 3 arranged symmetrically about a windmill rotary shaft 2, in which each blade 3 is supported with its peripheral end 7 rotatable, while the internal end 10 is displaced according to the rotating speed of the windmill, whereby the wind receiving surface assumes a paddle shape at starting in the standstill condition while it assumes a Savonius form in rotating, and when exceeding the rated rotating speed, the section shape in the axial direction assumes a cylindrical shape, which assures enhancement of the starting characteristic at starting and the power generating efficiency in rotating, and also suppression of the rise of the rotating speed in operating with strong winds, and thereby the power generator and/or the windmill is protected. COPYRIGHT: (C)2008,JPO&INPIT