Permanent-magnet rotor for electric motors and method of manufacturing the same

A permanent-magnet rotor for electric motors comprising:

• a shaft having a longitudinal extension;
• at least two semitubular permanent magnet segments arranged about said shaft;
• a molded casing including a central cylindrical portion interposed between said shaft and said permanent magnet segments;
• and
• a bottom flange portion connected to said permanent magnet segments and said shaft and said central cylindrical portion of said molded casing at a bottom end region of the rotor, said bottom flange portion comprising a bottom wall portion and a central hole in said bottom wall portion through which said shaft extends, said bottom flange further comprising an inner circumferential lip protruding from said bottom wall portion about said central hole in a direction substantially parallel to said longitudinal extension of the shaft in a space between said shaft and said permanent magnet segments, said inner circumferential lip engaging internal surface portions of said permanent magnet segments so as to retain said permanent magnet segments in position relative to said shaft whereby to properly form said central cylindrical portion of said molded casing between said shaft and permanent magnet segments, and said inner circumferential lip extending in said space between said shaft and said permanent magnet segments for a limited extent with respect to the extension of said shaft whereby for permitting said central cylindrical portion of said molded casing to be interposed between said shaft and said permanent magnet segments.