Patent ID: 8141201

Claim:
An electric fan, comprising: a motor that has a rotor; and an impeller that includes a main plate attached to an output shaft of the rotor and having a circular circumferential portion, a side plate disposed coaxially with the main plate with a predetermined spacing therebetween, the side plate having an edge portion that defines a central opening portion that allows an air flow to flow in, and the side plate having a circular circumferential portion, and a plurality of blades arranged between the main plate and the side plate, wherein a distance between the edge portion and a central rotation axis of the output shaft measured in a direction perpendicular to the central rotation axis is equal to or smaller than a distance between the central rotation axis and any other location on the side plate measured in a direction perpendicular to the central rotation axis, wherein the side plate of the impeller is formed so that the height thereof is lowered gradually from the edge portion toward the circular circumferential portion of the side plate, and when the distance from the edge portion of the central opening portion to the circular circumferential portion of the side plate, in a direction perpendicular to the output shaft, is taken as L, the distance from the edge portion of the central opening portion to the circular circumferential portion of the side plate, in the direction of the output shaft, is taken as H, a point on the side plate away from the edge portion of the central opening portion by 0.1×L in the direction perpendicular to the output shaft is taken as P, and the distance from the edge portion of the central opening portion to the point P in the direction of the output shaft is taken as ΔH, ΔH/H≧0.4 is satisfied.