Patent attributes
An axial fan includes an upper impeller disposed in an axially upper portion of a housing, and an upper circuit board disposed axially below the upper impeller. An upper impeller cup of the upper impeller includes an upper cylindrical portion and an upper lid. The axial fan includes a lower impeller disposed in an axially lower portion of the housing, and a lower circuit board disposed axially above the lower impeller. A lower impeller cup of the lower impeller includes a lower cylindrical portion and a lower lid. An axial upper end outer diameter of the upper cylindrical portion is smaller than an axial lower end outer diameter of the upper cylindrical portion. An axial lower end outer diameter of the lower cylindrical portion is smaller than an axial upper end outer diameter of the lower cylindrical portion.
