Method of producing a permanent magnet rotor

Claim 1

A method of producing a permanent magnet rotor, comprising the steps of: laminating a plurality of steel sheets to form a rotor yoke having 2n times (n is a positive integer) of magnetic poles on an outer periphery thereof, and a plurality of slots for receiving field permanent magnets at bases of all or every other magnetic poles at substantially equal distances from a rotatable shaft hole; making said field permanent magnets from a rare earth material; forming said field permanent magnets to a predetermined thickness; electrically nickel plating said field permanent magnets such that said nickel plating provides a plated layer having a thickness between 5 μm and 20 μm at a center of said field permanent magnets and has a substantially uniform thickness at said center and ends of said field permanent magnets without any electrode mark; disposing said plated field permanent magnets in said slots; heating said rotor yoke at a temperature above a curie point of said permanent magnets but below a temperature for retaining performance of said rare earth material; shrinkage fitting said heated rotor yoke to a rotatable shaft; and making magnetization of said rotor yoke.

Claim 2

A method of producing a permanent magnet rotor, comprising the steps of: laminating a plurality of steel sheets to form a rotor yoke having 2n times (n is a positive integer) of magnetic poles on an outer periphery thereof, and a plurality of slots for receiving field permanent magnets at bases of all or every other magnetic poles at substantially equal distances from a rotatable shaft hole; making said field permanent magnets from a rare earth material; forming said field permanent magnets to a predetermined thickness; electrically nickel plating said field permanent magnets such that said nickel plating provides a plated layer having a thickness between 5 μm and 20 μm at a center of said field permanent magnets and has a substantially uniform thickness at said center and ends of said field permanent magnets without any electrode mark; disposing said plated field permanent magnets in said slots; heating said rotor yoke at a temperature above a curie point of said permanent magnets but below a temperature for retaining performance of said rare earth material; shrinkage fitting said heated rotor yoke to a rotatable shaft; and making magnetization of said rotor yoke.

Claim 3

A method of producing a permanent magnet rotor, comprising the steps of: laminating a plurality of steel sheets to form a rotor yoke having 2n times (n is a positive integer) of magnetic poles on an outer periphery thereof, and a plurality of slots for receiving field permanent magnets at bases of all or every other magnetic poles at substantially equal distances from a rotatable shaft hole; making said field permanent magnets from a rare earth material; forming said field permanent magnets to a predetermined thickness; treating electroless nickel plating of said field permanent magnets at a temperature between 350° C. and 400° C.; disposing said plated field permanent magnets in said slots; heating said rotor yoke at a substantially same temperature as that of thermal treatment of said electroless nickel plating; and shrinkage fitting said heated rotor yoke to a rotatable shaft while doing said thermal treatment of said nickel plating.

Claim 4

A method of producing a permanent magnet rotor, comprising the steps of: laminating a plurality of steel sheets to form a rotor yoke having 2n times (n is a positive integer) of magnetic poles on an outer periphery thereof, and a plurality of slots for receiving field permanent magnets at bases of all or every other magnetic poles at substantially equal distances from a rotatable shaft hole; making said field permanent magnets from a rare earth material; forming said field permanent magnets to a predetermined thickness; treating electroless nickel plating of said field permanent magnets at a temperature between 350° C. and 400° C.; disposing said plated field permanent magnets in said slots; heating said rotor yoke at a substantially same temperature as that of thermal treatment of said electroless nickel plating; and shrinkage fitting said heated rotor yoke to a rotatable shaft while doing said thermal treatment of said nickel plating.