Brushless direct current electric motor with reduced cogging torque and production method thereof

A method for manufacturing a motor, the method comprising:

• a) stacking a plurality of metal rings to form a stator having a plurality of partitions extending radially outwardly from a cylindrical main body, each of the plurality of partitions including a flat end face for engaging an inner surface of a sleeve, the stator delimiting open volumes for receiving coils, the stacking carried out to a height corresponding to a length of the stator;
• b) winding copper wires around the partitions on the stack formed in step a);
• c) mounting, using a lacing technique, the stack obtained in step b) in the sleeve, with angular indexing by lugs and notches to position the stack in relation to the sleeve, wherein the sleeve includes:
• a plurality of deformation zones spaced around a circumference of the sleeve, the plurality of deformation zones adapted to maintain an outer circularity of said sleeve when mounting said stator in said sleeve when said end faces of the plurality of partitions of said stator are positioned adjacent associated ones of said plurality of deformation zones, wherein the plurality of deformation zones are formed by a plurality of cutouts provided in a wall of said sleeve;
• and
• a plurality of counterbores in the inner surface of the sleeve, each of said plurality of counterbores having a rounded bottom and extending over the length of an inner face of the sleeve, wherein only one of said plurality of counterbores is disposed between adjacent ones of said plurality of deformation zones;
• d) inserting a rotor into the stator;
• e) forming the part of the copper wires appearing on the ends or coil;
• and
• f) overmolding the assembled stator, rotor and sleeve with resin.