Patent ID: 7443064

Claim:
A permanent-magnet generator comprising: a flywheel having a ringlike portion and a bottom portion which closes off one end of the ringlike portion; a plurality of magnets arranged on an inside surface of the ringlike portion of said flywheel; a plurality of air passages formed in the bottom portion of said flywheel; a plurality of protrusions bulging inward from the bottom portion of said flywheel; and a coil disposed to face said magnets for generating electricity by virtue of electromagnetic induction caused by relative movement of said coil and said magnets; wherein an irregular surface portion is formed in each of said protrusions, said irregular surface portion being configured so as to create a turbulent air flow when said flywheel rotates, said irregular surface portion being irregularly shaped along a circumferential direction of said flywheel, and wherein the irregular surface portion of each of said protrusions comprises at least two steps on each side of said protrusions, in said circumferential direction of said flywheel, and wherein each respective protrusion is located in between two respective adjacent air passages.