Winding slot-embedded vapor chambers and heat pipes with endcap heat sinks for electric machines

An electric machine, comprising:

• a housing;
• a stator assembly including a stator core attached to the housing and an electromagnetic stator winding mounted in a stator slot of the stator core;
• a rotor assembly including a rotor core rotatably attached to the housing adjacent the stator assembly and an electromagnetic rotor winding mounted in a rotor slot of the rotor core, the rotor winding configured to magnetically mate with the stator winding;
• a heat pipe mounted in the rotor slot adjacent the rotor winding and projecting axially from an axial end of the rotor core, the heat pipe including:
• a sealed canister containing a working fluid configured to change phases between
• a liquid phase and a gas phase to thereby passively extract thermal energy from the rotor winding and transmit the extracted thermal energy out from the rotor core through the axial end of the rotor core;
• a wick structure located inside the sealed canister and configured to transfer the working fluid, when in the liquid phase, from axial ends of the sealed canister to a central region of the sealed canister,
• wherein the wick structure abuts an interior surface of the sealed canister and defines an elongated central vapor channel configured to pass the working fluid, when vaporized to the gas phase, to the axial ends of the sealed canister and pass the working fluid, when condensed to the liquid phase, into the wick structure.

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 in a stator slot of 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 in a rotor slot of the rotor core;
• mounting a heat pipe in the rotor slot such that the heat pipe is adjacent the rotor winding and projects axially from an axial end of the rotor core, wherein the heat pipe is configured to passively extract thermal energy from the rotor winding and transfer the thermal energy out from the rotor core;
• attaching a rotor endcap adjacent the axial end of the rotor core such that the rotor endcap abuts a longitudinal end of the heat pipe to receive therefrom the extracted thermal energy transferred out from the rotor core, the rotor endcap including a heat pipe cavity recessed into an axial surface of the rotor endcap and nesting therein the longitudinal end of the heat pipe.