Patent ID: 7327055

Claim:
In a permanent magnet generator, the combination of: a generator housing; a sealed stator housing within said generator housing, said stator housing carrying stator windings and having an outer surface being fitted with external fins, said fins surrounded by a sleeve extending generally axially from front to rear along said stator housing external surface; a hollow shaft rotatably mounted within said stator housing, said shaft carrying permanent magnets which interact with said stator windings, said hollow shaft having an air channel communicating therethrough an inlet end and an outlet end whereby said permanent magnets are sealed from the outside environment; a fan mounted on said hollow shaft; a cylindrical aluminum sleeve mounted inside said hollow shaft; means for rotating said shaft; whereby said stator housing is fit within said generator housing such that there is a space between said housings and when said generator is in operation, said fan draws cooling air forward through said cylindrical aluminum tube in said rotor shaft and ejects said air through said space between said stator housing and said generator housing over said stator housing external fins into the atmosphere; and thereby cools said generator, said stator and permanent magnets being sealed from the outside environment whereby the cooling air does not transverse and flow into the interior of the generator.