Patent ID: 9605686
Date: 2017-03-28
CPC Classifications: F04D,F05D,F24F

Claim:
1. An axial flow fan comprising: a plurality of blades rotated to deliver a fluid from an upstream side to a downstream side of a flow of the fluid in a direction along an axis of rotation, each of the plurality of blades including: a first curved portion formed on a leading edge on a forward side of the blade in a rotational direction in which the blade rotates, the first curved portion protruding backwards in the rotational direction in a planar image of the blade as projected in the direction along the axis of rotation, and the first curved portion having a leading-edge rearmost point as a point of contact where the first curved portion is in contact with a virtual line that extends perpendicularly to the axis of rotation; a second curved portion formed on a trailing edge on a backward side of the blade in the rotational direction, the second curved portion being located on an inner circumferential side of the trailing edge and protruding backwards in the rotational direction in a planar image of the blade as projected in the direction along the axis of rotation; and a third curved portion formed on the trailing edge on the backward side of the blade in the rotational direction, the third curved portion being located on an outer circumferential side of the blade on the trailing edge and protruding forwards in the rotational direction in a planar image of the blade as projected in the direction along the axis of rotation, the third curved portion having a trailing-edge foremost point as a point of contact where the third curved portion is in contact with another virtual line that extends perpendicularly to the axis of rotation, and the second curved portion having a trailing-edge rearmost point at which a length of a perpendicular line dropped to the other virtual line that passes through the axis of rotation and the trailing-edge foremost point takes a maximum, wherein a first intersection that is an intersection between the trailing edge and a first concentric circle, which is one of concentric circles having as their center the axis of rotation and passes through the leading-edge rearmost point, is located between the trailing-edge rearmost point and the trailing-edge foremost point.