US Patent 9030062 Cooling structure of rotating electric machine

A cooling structure of a rotating electric machine includes a rotor core formed of a plurality of electromagnetic steel plates and a resin molding portion molding the rotor core with resin. The rotor core is provided with a through hole passing therethrough in the axial direction of the central axis that is a rotation axis. The rotor core is provided inside the through hole with an oil passage through which oil circulates. The resin molding portion has a cover portion covering the outer peripheral side of the oil passage. This configuration can provide the cooling structure of the rotating electric machine that achieves efficient cooling while suppressing occurrence of energy loss.