| 摘要 |
A vertical axis wind turbine comprises a plurality of sails (blades) arranged about the axis so as to provide rotation of the turbine, each sail having relatively foldable wind engaging sections. When the sails are moving in a downstream direction they are unfolded so as to provide a maximum wind engaging area, and when they are moving in an upstream direction they are folded so as to provide a lower wind engaging area; preferably about 25% of the maximum area. The sails have a length to width ration of 2:1, and a first fold is provided between the centre points of the two longer sides. Two further folds are provided diagonally from one end of the first fold to the opposite corner of the respective halves of the sail. Stabiliser rods are used to maintain the shape of the sails, and springs are provided to assist the folding operation. |
