US Patent 7438531 Fan and rotor structure thereof

A fan and a rotor structure thereof. The rotor structure has a case, an upper linking structure, a lower structure, and a rotating shaft. The case has an opening at the axle center. The upper linking structure has a fixing portion and a threaded portion. The minimum radius of the fixing portion is longer than the radius of the opening. The threaded portion is disposed in the opening. The lower linking structure has a thread corresponding to the threaded portion. The upper linking structure and the lower linking structure is screwed together to secure the case therebetween. The rotating shaft is fixed in the upper linking structure or the lower linking structure.