Patent ID: 8562471

Claim:
An electric motor assembly comprising: a stator with electrical windings; a rotor assembly rotatable about an axis of rotation and having: a rotor hub having first and second rotor hub portions; a rotor supported on the rotor hub, the rotor having first and second annular rotor segments with the first annular rotor segment supported for rotation with the first rotor hub portion and the second annular rotor segment supported for rotation with the second rotor hub portion, each of the rotor segments having a respective set of magnets spaced circumferentially therearound; wherein the rotor hub portions and rotor segments are configured so that at least one of the rotor segments moves about the axis of rotation relative to the other of the rotor segments as the rotor hub rotates; wherein the movement of the at least one of the rotor segments is by an amount that increases as the speed of the rotor hub increases to reduce back electromotive force; wherein one of the rotor hub portions defines a lubrication flow channel that extends from an inner diameter of said one of the rotor hub portions to an outer diameter of said one of the rotor hub portions; wherein the first and second rotor hub portions define a cavity therebetween; wherein the first rotor hub portion has a first set of vanes extending into the cavity; wherein the second rotor hub portion has a second set of vanes extending into the cavity; and wherein the first and second sets of vanes are configured to be pushed apart from one another when fluid is forced radially outward from the flow channel to the cavity, thereby causing the movement of the at least one rotor hub portions about the axis of rotation relative to the other of the rotor hub portions.