Axial flow fan

A fan comprising:

• a motor part arranged to rotate about a center axis extending up and down;
• an impeller including a plurality of blades extending radially outward, the impeller being fixed to the motor part;
• a housing arranged to surround outer peripheries of the motor part and the impeller, the housing including a cylindrical inner circumferential surface;
• and
• a plurality of ribs arranged to interconnect the motor part and the housing,
• wherein the housing includes an intake port which is an upper opening of the housing, an upper edge which surrounds the intake port, an exhaust port which is a lower opening of the housing, a lower edge which surrounds the exhaust port, and a flow straightening grid disposed in the upper edge, and
• an axial distance from an upper end of each of the blades to a lower end of the flow straightening grid is ½ times or more of an axial distance from the upper end of each of the blades to a lower end thereof.