Motor including embedded permanent-magnet rotor and method for making same

A method of forming a rotor for use in an electrical device having a high torque to size ratio, comprising:

• forming an annular array of multiple pie-shaped lamination segments each having radially extending sides and a radially outward peripheral edge and a radially inward peripheral edge, said segments being arrayed around a center axial opening and with plate magnets oriented radially of said array between said segments, said magnets being magnetized through their thicknesses so that the magnetic poles of each magnet are at side surfaces thereof which face the two adjacent segments and with the poles of the magnets facing each side of each segment being of the same polarity;
• connecting the laminations of each of said segments to one another in areas radially outward of said shaft without magnetically conductive components other than said segments and said magnets,
• providing a rotor drive shaft,
• assembling said drive shaft and said array of segments with said drive shaft extending through said center axial opening,
• affixing a first abutment support to said drive shaft in a predetermined position;
• assembling said annular array of segments on said shaft whereby said shaft extends through said center axial opening and one end of said segments abuts said first abutment support;
• compressing said laminations against said first abutment support by moving a second abutment support against the opposite end of said segments;
• and
• securing said second abutment support to said shaft adjacent said other end of said segments,
• maintaining each of said first and second abutment supports in compressive relation against the respective end of said segments solely by axial forces transmitted to said shaft by said first and second abutment supports,
• whereby said segments, said abutment supports and said drive shaft form a rigid rotor that provides high torque output in an electric device using said rotor.