Centrifugal fan device

A centrifugal fan device, comprising:

• an impeller supported to rotate about a center axis extending in an up-down direction;
• a motor arranged to rotate the impeller;
• and
• a housing arranged to surround the impeller;
• wherein
• the housing includes an intake portion positioned above the impeller and an exhaust portion positioned radially outward of the impeller;
• the impeller includes a lower impeller member and an upper impeller member positioned above the lower impeller member;
• and
• one of the lower impeller member and the upper impeller member includes a plurality of recesses, the other of the lower impeller member and the upper impeller member including a plurality of protrusions being fitted to the recesses;
• the recesses includes a single different-diameter recess differing in diameter from the remaining recesses, the protrusions including a single different-diameter protrusion differing in diameter from the remaining protrusions, the different-diameter protrusion fitted to the different-diameter recess.

A centrifugal fan device manufacturing method comprising:

• providing a centrifugal fan device including an impeller supported to rotate about a center axis extending in an up-down direction, a motor arranged to rotate the impeller and a housing arranged to surround the impeller, the housing including an intake portion positioned above the impeller and an exhaust portion positioned radially outward of the impeller, the impeller including a lower impeller member and an upper impeller member positioned above the lower impeller member;
• inspecting gravity center deviations of the lower impeller member and the upper impeller member;
• setting positions of a single different-diameter recess and a single different-diameter protrusion such that, when the lower and upper impeller members are combined together, the gravity center deviations of the lower and upper impeller members are in the substantially opposite directions;
• and
• combining the lower and upper impeller members such that the single different-diameter recess and the single different-diameter protrusion are aligned with each other.