Abstract: A rotor assembly for an alternator includes an electrical wire defining an excitation winding. A first pole piece and a second pole piece each have a generally circular body defining an axis of rotation and an outer radial periphery. A plurality of pole fingers are spaced radially about and extend axially from the outer radial periphery of each pole piece parallel to the axis of rotation. Each pole piece includes a plurality of mounting surfaces spaced radially about the outer radial periphery between the pole fingers. A plurality of permanent magnets are positioned on the mounting surfaces, each of the permanent magnets being secured to the pole pieces by a threaded fastener extending therethrough and engaging the pole pieces.

Abstract: In an alternating current generator, a rotor is provided radially inside a stator core. A rotor core has a cylindrical boss press-fit around a rotor shaft, disc portions extending from an outer periphery of the boss in a radial direction, and claw pieces in connecting with the disc portions radially outside the boss. A field winding is provided between the boss and claw pieces. An annular core is provided on an outer periphery of the claw pieces. The annular core is made of a stack of core sheets and has slits formed in the radial direction. Iron loss is decreased and leaks of magnetic fluxes in the annular core are suppressed by the slits.

Abstract: A rotor of a motor has a cylindrical magnet coaxially disposed with a shaft. The shaft and the magnet are bonded with thermosetting resin formed by injection molding. Since the molding shrinkage of the thermosetting resin is so small that a high preciseness is achieved in the motor structure. This precision structure can reduce vibration due to unbalance of a rotor. Also, an annealing process, in which a motor is left at a temperature higher than the limit temperature for operating the motor, can be eliminated. As a result, the efficiency of producing the motor can be improved.

Abstract: A rotor structure comprising magnets for suppressing the leakage of a magnetic flux between the side faces of the adjacent claw-like magnetic poles and metal holding members each of which covers the magnets together with the claw-like magnetic pole and radiates heat transmitted to the claw-like magnetic pole at the time of power generation. Therefore, the quantity of heat radiated to the peripheral portions of the magnets is increased and the coolability of the magnets can be greatly improved.