Patent ID: 8169118

Claim:
An electromagnetic actuator comprising: a body having a rotational axis; at least three radial magnetic pole assemblies, each circumferentially arranged around the rotational axis, separated from the body by radial gaps, and distributed along the rotational axis at fixed distances from each other, each radial magnetic pole assembly comprising: a plurality of radial poles adjacent and spaced apart from a lateral facing surface of the body and configured to communicate magnetic flux with the lateral facing surface of the body, and the plurality of radial poles of the respective radial magnetic pole assembly and the body magnetically coupled and defining a radial magnetic control circuit; an excitation coil around each of the plurality of radial poles configured to produce control magnetic flux in the radial magnetic control circuits; and a plurality of magnetic elements distributed with alternating polarities along the rotational axis, each of the magnetic elements residing between adjacent radial magnetic pole assemblies and configured to produce bias magnetic fluxes flowing radially within each adjacent radial magnetic pole assembly and axially in the body between adjacent radial magnetic pole assemblies.