Patent ID: 8029251
Filing Date: 2011-10-04
Classification: F04D

Abstract:
1. A fan comprising: an impeller rotatable about an axis to generate an air flow; and a motor operable to rotate the impeller about the axis and including a rotor having a substantially cylindrical outer side surface; wherein the impeller includes an impeller cup including a surrounding wall which is substantially cylindrical about the axis and a plurality of blades integral with the impeller cup, the blades being arranged outside the surrounding wall of the impeller cup in a radial direction that is perpendicular or substantially perpendicular to the axis; an outer surface of the surrounding wall of the impeller cup defines a portion of a truncated circular cone with an outer diameter of the surrounding wall increasing from a top side to a bottom side in an axial direction that is parallel or substantially parallel to the axis; an inner substantially cylindrical surface about the axis is provided inside the surrounding wall with a gap interposed between the inner substantially cylindrical surface and the outer surface of the surrounding wall, the gap being opened toward the bottom side in the axial direction; the outer side surface of the rotor is connected to an inside of the inner substantially cylindrical surface of the impeller cup coaxially therewith; the inner substantially cylindrical surface of the impeller cup includes a plurality of elongated projections which project inwardly in the radial direction, extend along the axial direction, and are circumferentially arranged about the impeller cup; an outer substantially cylindrical surface of the impeller cup includes a plurality of ribs; and a total number of the plurality of blades, a total number of the plurality of elongated projections, and a total number of the plurality of ribs are each equal to each other, and the plurality of blades, the plurality of elongated projections, and the plurality of ribs are arranged at the same circumferential positions such that respective ones of the plurality of blades, the plurality of elongated projections, and the plurality of ribs are aligned with each other in the radial direction.