Blower fan

A blower fan comprising:

• an impeller centered on a central axis extending in a vertical direction;
• a motor portion arranged to rotate the impeller about the central axis;
• and
• a housing arranged to house the impeller;
• wherein
• the housing includes:
• a lower plate portion arranged to cover a lower side of the impeller, and arranged to have the motor portion fixed thereto;
• and
• a side wall portion arranged to cover a lateral side of the impeller;
• the lower plate portion or an upper plate portion arranged to cover an upper side of the impeller includes an air inlet;
• the upper plate portion, the side wall portion, and the lower plate portion are arranged to together define an air channel portion arranged to surround the impeller;
• the upper plate portion, the side wall portion, and the lower plate portion are arranged to together define an air outlet on the lateral side of the impeller;
• the air outlet is planar and parallel to the central axis, and includes one of an edge of the upper plate portion, a pair of edges of the side wall portion, and an edge of the lower plate portion that is closest to the central axis;
• the side wall portion includes a tongue portion arranged to project between the air outlet and the impeller;
• a side surface of the tongue portion includes:
• a tongue portion tip arranged to touch a first imaginary plane including the central axis;
• a first tongue portion side surface arranged to extend from the tongue portion tip along an outer envelope of the impeller;
• and
• a second tongue portion side surface arranged to extend from the tongue portion tip toward a side edge, the side edge being a line of intersection of the air outlet and the side wall portion;
• the second tongue portion side surface is arranged to cross a second imaginary plane including the central axis and touching the side edge;
• and
• a closest proximity position, at which the first tongue portion side surface and the outer envelope are in closest proximity to each other, is located between the first imaginary plane and a third imaginary plane including the central axis and touching the second tongue portion side surface between the tongue portion tip and the side edge.