Closed-circuit rotor cooling arrangement and electric machine having same

Abstract

A rotor cooling arrangement is provided for an electric machine used in a drive train of a work vehicle. The electric machine has a housing containing a stator disposed within the housing in a fixed position about a rotation axis. The rotor cooling arrangement includes a rotor disposed within the housing about the rotation axis. The rotor has a series of rotor discs with pockets in which magnets are disposed. The rotor discs are separated from each other along the rotation axis by a dielectric. A rotor shaft extends along the rotation axis and couples to the rotor discs to corotate relative to the stator about the rotation axis. The rotor shaft defines, in part, a cooling circuit through which flows coolant for cooling the rotor. The cooling circuit includes a feed passage internal to the rotor shaft that communicates with a cooling passage, in the form of an open groove in an outer surface of the rotor shaft, that communicates with an outlet opening spaced along the rotation axis from the rotor. The rotor closes off the open groove such that the cooling circuit is a closed loop circuit in which coolant circulates through the rotor shaft from the feed passage to the cooling passage to the outlet opening.