Patent ID: 9670932
Date: 2017-06-06
CPC Classifications: F04D

Claim:
1. A fan comprising: an impeller; a motor portion arranged to rotate the impeller about a central axis extending in a vertical direction; a housing arranged to surround an outer circumference of the impeller; and a plurality of ribs, each of which is arranged to join the motor portion and the housing to each other; wherein the impeller includes a plurality of blades arranged to extend radially outward from the central axis; an upper opening of the housing in the vertical direction is an air inlet, while a lower opening of the housing is an air outlet; the housing includes a plurality of decreased thickness portions and a plurality of increased thickness portions arranged alternately in a circumferential direction extending about the central axis; a diameter of an inner circumferential surface of the housing is arranged to increase with a decreasing height in the vertical direction between the air inlet and an axial middle portion of a radially outer edge of each blade of the plurality of blades; below the axial middle portion of the radially outer edge of each blade of the plurality of blades, the diameter of the inner circumferential surface of the housing is arranged to increase with the decreasing height in the vertical direction, to be uniform, or to increase with the decreasing height in the vertical direction while being uniform over at least one area; a distance between the central axis and the radially outer edge of each blade of the plurality of blades is arranged to increase from the air inlet toward the air outlet; the inner circumferential surface of the housing has a minimum radius smaller than a distance between the central axis and an outermost portion of the radially outer edge of each blade of the plurality of blades; the housing includes: at a boundary between the upper and lower housing portions, the inner circumferential surface of the housing has a radius greater than the distance between the central axis and the outermost portion of the radially outer edge of each blade of the plurality of blades; the lower housing portion, the plurality of ribs, and a base portion of the motor portion are defined by a single continuous monolithic member; the increased thickness portions include a plurality of component fastening structures defining a fastening structure arranged to fit the upper and lower housing portions to each other; the plurality of component fastening structures include: either the first housing segment includes auxiliary projecting portions, each of which is positioned in the increased thickness portions adjacent to corresponding ones of the plurality of projecting portions, the auxiliary projecting portions are arranged to extend toward the second housing segment, and the second housing segment includes auxiliary recessed portions, each of which is arranged to have a separate one of the auxiliary projecting portions fitted thereinto; or the second housing segment includes auxiliary projecting portions, each of which is positioned in the increased thickness portions adjacent to corresponding ones of the plurality of projecting portions, the auxiliary projecting portions are arranged to extend toward the first housing segment, and the first housing segment includes auxiliary recessed portions, each of which is arranged to have a separate one of the auxiliary projecting portions fitted thereinto; and in the circumferential direction extending about the central axis when viewed from an air inlet end toward an air outlet end of the central axis, one of the auxiliary projecting portions is provided on a clockwise side of a corresponding one of the plurality of projecting portions and all remaining ones of the auxiliary projecting portions are provided on counterclockwise sides of all remaining corresponding ones of the plurality of projecting portions, every one of the increased thickness portions includes one of the plurality of projecting portions and one of the auxiliary projecting portions.