Rotor shaft-mounted vapor chambers and heat pipes with endcap heat sinks for electric machines

A motor vehicle comprising:

• a vehicle body;
• a plurality of road wheels attached to the vehicle body;
• a rechargeable energy storage system (RESS) attached to the vehicle body;
• and
• a traction motor attached to the vehicle body, electrically connected to the RESS, and configured to drive one or more of the road wheels to thereby propel the motor vehicle, the traction motor including:
• a motor housing;
• a stator assembly rigidly mounted inside the motor housing, the stator assembly including an annular stator core and a plurality of electromagnetic stator windings mounted in circumferentially spaced stator slots of the stator core;
• a rotor assembly rotatably mounted inside the motor housing adjacent the stator assembly, the rotor assembly including a cylindrical rotor core nested inside the annular stator core and a plurality of electromagnetic rotor windings mounted in circumferentially spaced rotor slots of the rotor core;
• a rotor power transfer circuit (PTC) mounted inside the motor housing, spaced axially from the rotor core, and electrically connected to the rotor assembly to selectively electrify the rotor windings;
• a rotor shaft circumscribed by and attached to the rotor core to rotate in unison therewith;
• and
• a plurality of heat pipes mounted on an outer-diameter (OD) surface of and spaced circumferentially around the rotor shaft, each of the heat pipes being configured to passively extract thermal energy from the rotor PTC and transfer the thermal energy out of the rotor PTC.

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

• receiving a housing of the electric machine;
• attaching a stator assembly to the housing, the stator assembly including a stator core and an electromagnetic stator winding mounted to the stator core;
• attaching a rotor assembly to the housing such that the rotor assembly is adjacent and rotatable with respect to the stator assembly, the rotor assembly including a rotor core and an electromagnetic rotor winding mounted to the rotor core;
• attaching a rotor power transfer circuit (PTC) to the housing such that the rotor PTC is spaced axially from the rotor core and electrically connected to the rotor assembly to electrify the rotor winding;
• attaching a rotor shaft to the rotor core to rotate in unison therewith;
• and
• mounting a heat pipe on an outer surface of the rotor shaft such that the heat pipe projects axially between the rotor PTC and the rotor core, the heat pipe being configured to passively extract thermal energy from the rotor PTC and transfer the thermal energy out of the rotor PTC.