Fan rotor assembly

A fan rotor assembly comprising:

• an inner rotor formed from a metal sheet, formed integrally in to one piece and having
• an inner disk having a diameter, a top surface, a bottom surface, an outer edge being annular and a central hole defined through the inner disk;
• multiple first connecting tabs formed and protruding perpendicularly down from the outer edge at first intervals and each first connecting tab having an inner surface;
• multiple first blades formed on and protruding outward respectively from the first connecting tabs;
• and
• multiple notches defined radially in the outer edge of the inner disk, corresponding respectively to the first intervals and located respectively between adjacent first connecting tabs;
• an outer rotor formed from a metal sheet, formed integrally into one piece, stacked over the inner rotor and having
• an outer disk mounted on the inner disk and having a diameter being equal to the diameter of the inner disk, a top surface, a bottom surface abutting the top surface of the inner disk, an outer edge being annular and a central hole defined through the outer disk;
• multiple second connecting tabs formed on and protruding perpendicularly down from the outer at second intervals and engaged respectively with the notches in the inner rotor so that the second connecting tabs are flush with and arranged alternately with the first connecting tabs, and each second connecting tab having an inner surface;
• and
• multiple second blades formed on and protruding outward respectively from the second connecting tabs and being flush with and arranged alternately with the first blades in a same circle;
• a central retainer mounted through the central holes in the inner and outer rotors;
• and
• a central shaft mounted in the central retainer under the inner rotor.