Electric machine with rotor coolant and lubrication distribution system, and systems and methods of cooling and lubricating an electric machine

A method of cooling an electric machine, the method comprising:

• injecting a coolant into a first end of a hollow region of a rotor shaft of an electric machine;
• rotating the rotor shaft at an operational rate of rotation, the rotating generating a force comprising a centrifugal force acting upon the coolant in the rotor shaft, the force causing the coolant to flow across an inner surface of the rotor shaft from the first end to a second end;
• and
• transferring heat from the rotor shaft to the coolant flowing across the inner surface of the rotor shaft;
• wherein the electric machine comprising a stator, a rotor, an impeller comprising an annular body mounted on the rotor shaft, the rotor shaft fitting within an annular space defined by the annular body, and the rotor shaft operably coupled to the rotor, wherein the inner surface of the rotor shaft has a slope that increases from a first inner diameter at the first end to a second inner diameter at the second end, the slope comprising a frustoconical or sloped profile and/or a stepped profile;
• and
• wherein the impeller comprises a plurality of impeller blades and a corresponding plurality of impeller channels transitioning from a radial orientation to an axial orientation, the plurality of impeller blades and the corresponding plurality of impeller channels configured to scoop or push the coolant through a plurality of coolant supply holes in the rotor shaft and into the first end of the hollow region of the rotor shaft.