US Patent 9435350 Air blowing device

An air blowing device includes a housing with a suction port and a blow-off port, and a fan placed in the housing. The fan includes a fan case with a tongue section, an impeller, and a motor. The fan case includes an inlet and an outlet, and is shaped such that a space between the impeller and an inner wall of the fan case increases along a rotary direction of the impeller up to a cross section cut along a line between the tongue section and its opposite section. An opening area of the fan case at the tongue section is kept equal or decreases up to the outlet.