Permanent magnet rotor

A rotor for an electric motor comprising a ferromagnetic core having an axial bore, a plurality of magnetizable elements positioned about the core, and a retaining shell having a relatively thin annular wall portion pressed longitudinally over the magnetizable elements so that said wall portion is forced to conform to outer contours of said magnetizable elements to retain the magnetizable elements in longitudinally fixed relation on the core.

A rotor for an electric motor comprising a ferromagnetic core having an axial bore, a plurality of magnetizable elements positioned about the core, said magnetizable elements having longitudinal lengths less than an axial length of the core, at least one end plate axially engaging an end of said core, a retaining shell pressed longitudinally over the magnetizable elements so as to retain the magnetizable elements in longitudinally fixed relation on the core, said shell having at least one end portion formed generally radially inwardly so as to engage and retain said end plate against the adjacent end of said core with a gap being established between said end plate and adjacent ends of said magnetizable elements, and a curable adhesive interposed between said adjacent ends of said magnetizable elements and said end plate so as to establish a void between said end plate and the adjacent ends of said magnetizable elements, said void comprising approximately 20% of the gap when the adhesive is cured.

A rotor for an electric motor comprising a ferromagnetic core having an axial bore, a plurality of magnetizable elements positioned about the core, said magnetizable elements having longitudinal lengths less than an axial length of the core, end plates axially engaging opposite ends of said core, a retaining shell pressed longitudinally over the magnetizable elements so as to retain the magnetizable elements in longitudinally fixed relation on the core, said shell having end portions formed generally radially inwardly so as to engage and retain said end plates against the opposite ends of said core with a gap being established between at least one of said end plates and adjacent ends of said magnetizable elements, and a curable adhesive disposed in said gap in an amount to fill between approximately 40%-80% of said gap when said adhesive is cured.

A permanently magnetizable rotor which comprises:

• a core, a plurality of magnetizable elements circumferentially spaced around the core, a pair of end rings disposed axially against opposite ends of the core, and a retaining shell having a wall portion forced longitudinally over outer contours of said magnetizable elements so as to retain the magnetizable elements in position around the core and retain the end rings in position against the core ends, at least some of said magnetizable elements having shorter longitudinal length than said core so as to create a gap between at least one end of each of said shorter length magnetizable elements and adjacent opposed end ring.

A permanently magnetizable rotor which comprises:

• a core, a plurality of magnetizable elements circumferentially spaced around the core, a pair of end rings disposed axially against opposite ends of the core, and a retaining shell disposed so as to retain the magnetizable elements in position around the core and retain the end rings in position against the core ends, at least some of said magnetizable elements having shorter longitudinal lengths than said core so as to create a gap between at least one end of each of said shorter length elements and an adjacent end ring, a portion of said retaining shell extending beyond the end rings, said portion of said retaining shell extending beyond the end rings being deformed inwardly toward a central axis of the shell to retain the end rings against the ends of said core.

Art electronically commutated motor having a stator assembly with a centrally located bore and a rotor assembly disposed within said bore, said rotor assembly comprising a ferromagnetic core having an axial bore, a plurality of magnetizable elements positioned about the core, and a retaining shell having a generally cylindrical tubular wall portion pressed longitudinally over the magnetizable elements and stretched so as to conform to outer contours of the magnetizable elements, said shell being a thin-walled shell having a wall thickness of less than 0.020".