Blower and vacuum cleaner

A blower comprising:

• an impeller rotatable about a central axis extending in a vertical direction;
• a motor that is positioned on a lower side of the impeller and rotates the impeller about the central axis;
• and
• a duct including an airflow passage in an inner space, a suction port through which a fluid flows in the inner space, and an air outlet through which the fluid is discharged from the inner space, the impeller being accommodated in the duct;
• wherein
• the impeller includes:
• a plurality of blades arranged in a circumferential direction;
• a shroud that has an annular shape, connects upper portions of the plurality of blades, and includes an opening located opposite to the suction port in an axial direction;
• and
• a base plate that connects lower portions of the plurality of blades and extends in a radial direction;
• wherein
• the duct includes a cover covering at least a portion of the plurality of blades and an upper portion of the shroud;
• an inner diameter of the shroud is equal to or larger than an outer diameter of the base plate;
• and
• the cover includes a projection that projects axially downward from a bottom surface of the cover and is disposed on a radial interior of an inner circumferential surface of the shroud.