Rotor assembly with permanent magnets and method of manufacture

摘要

A permanent magnet rotor assembly comprises a cylindrically shaped shaft (1) having an outer surface, a plurality of permanent magnets (22) constituting portions of annular segments and an outer retaining cylindrical sleeve (23) surrounding the plurality of permanent magnets (22). The assembly further comprises a cylindrical magnet housing (21) mounted on the cylindrically shaped shaft (1) for supporting the plurality of permanent magnets (22). The cylindrical magnet housing (21) is formed of a magnetic material. The retaining cylindrical sleeve (23) is preloaded by a resultant interference fit IF2 which is defined by the following formula: IF �¢ 2 = - ˆY + ˆ �¢ Y + IF �¢ 1 ˆ§ �¢ 2 + ˆ �¢ Y ˆ§ �¢ 2 - ˆ �¢ X ˆ§ �¢ 2 ,
where ¦Y is an external diameter of the plurality of permanent magnets (22), ¦X is an internal diameter of the cylindrical magnet housing (21), and IF1 is a primary interference fit between an external diameter of the cylindrically shaped shaft (1) and the internal diameter of the cylindrical magnet housing (21).