Windmill having blades which alter their pitch angles automatically in response to both wind speed and load

摘要

A windmill includes a hub assembly (13) connected to a shaft (3) and having a plurality of blades (6) extending therefrom. Each blade comprises an inner section (6a) hingeably connected to a hub member (14) along a first axis (8) and an outer section (6b) hingeably connected to the inner portion along a second hinge axis (7) extending from a point on the trailing edge (11) of the blade adjacent the first hinge axis to a point on the leading edge (12) remote from the first hinge axis. The blades are resiliently biased towards a rest position wherein the inner section of each blade lies in a plane at an angle to the plane of rotation of the blades and the outer sections extend outwardly in a plane at an angle to the plane of the inner section and at a pitch angle to the plane of rotation. The configuration is such that the blades vary their pitch angles automatically in response to variations in wind speed and in the torsional load applied to the shaft, decreasing in pitch in response to increasing wind speed and increasing in pitch in response to increasing load.