Vertical blade having a vertical main part and inwardly inclined parts and a vertical shaft wind turbine using the vertical blade

A vertical shaft wind turbine comprising:

• a plurality of blade sets, wherein each blade set comprises at least two vertical blades,
• wherein, for each vertical blade,
• the vertical blade comprises a vertical main part, an upper inwardly inclined part and a lower inwardly inclined part,
• the vertical main part extends in a vertical direction which is defined by a rotational axis of a vertical main shaft of the wind turbine, the vertical main part has upper and lower ends that merge with the upper and the lower inwardly inclined parts, respectively, such that the vertical main part is centrally located in the vertical direction between the upper and the lower inwardly inclined parts,
• the upper inwardly inclined part has a tip on an end thereof opposite from the vertical main part, the upper inwardly inclined part extends from the upper end of the vertical main part diagonally upward and linearly toward the vertical main shaft,
• the lower inwardly inclined part has a tip on an end thereof opposite from the vertical main part, the lower inwardly inclined part extends from the lower end of the vertical main part diagonally downward and linearly toward the vertical main shaft,
• the tip of the upper inwardly inclined part is fixed to an upper mounting member which is fixed to an upper part of the vertical main shaft, and the tip of the lower inwardly inclined part is fixed to a lower mounting member which is fixed to a lower part of the vertical main shaft, such that the vertical blade is rigidly fixed to the vertical main shaft of the wind turbine and such that the vertical blade rotates with the vertical main shaft when the vertical main shaft rotates about the rotational axis in a rotational direction,
• the vertical blade is formed such that a chord length and a thickness of the vertical blade are continuously reduced from the upper and the lower ends of the vertical main part, respectively, to each of the tips of the upper and the lower inwardly inclined parts, and, in the vertical direction, the chord length of the vertical blade is greatest centrally between the upper and the lower ends of the vertical main part, and
• a cross sectional shape of the vertical main part is an airfoil shape, and the vertical main part of the vertical blade has a chord length that is in a range of 45% to 55% of a radius of rotation of the vertical main part, the radius of rotation being a distance from the rotational axis to a chord of the vertical main part,
• wherein the blade sets are arranged in layers in the vertical direction, the layers of blade sets including at least a blade set of a lower layer and a blade set of an upper layer,
• wherein tips of upper inwardly inclined parts of the blade set of the lower layer are positioned midway, in the vertical direction, between tips of upper inwardly inclined parts of the blade set of the upper layer and tips of lower inwardly inclined parts of the blade set of the upper layer, and
• wherein the tips of the lower inwardly inclined parts of the blade set of the lower layer are positioned below, in the vertical direction, the tips of the lower inwardly inclined parts of the blade set of the upper layer.