A shaft (12) for cooling an electric machine (10) includes: an outer sub-shaft (32), which is designed for being rotationally fixed to a rotor (14) of the electric machine; an inner sub-shaft (30), which is rotationally fixed to the outer sub-shaft and is designed as an output shaft of the electric machine; an inflow (36) arranged in the radial direction between the outer sub-shaft and the inner sub-shaft, in order to supply cooling fluid (28) to the shaft; and an outflow (42) arranged in the radial direction between the outer sub-shaft and the inner sub-shaft, in order to discharge cooling fluid supplied to the shaft. The outer sub-shaft encloses a fluid chamber (40), which is arranged in the axial direction between the inflow and the outflow. A direction of flow of cooling fluid in the fluid chamber is established by a delivery direction of a fluid pump (24).

A drive apparatus includes: a motor having a shaft; a bearing rotatably supporting the shaft; a housing for the motor and holding the bearing in a bearing holding portion; an insulating member between the bearing and the bearing holding portion; and an oil passage. The bearing holding portion includes a holding tubular portion holding the bearing from radially outside, and a holding bottom portion extending radially inward from an end on one side in the axial direction of the holding tubular portion. The insulating member includes an insulating tubular portion extending in the axial direction along the holding tubular portion, and an insulating bottom portion extending in the radial direction along the holding bottom portion. The holding tubular portion has a penetrating portion penetrating radially inside and outside. The oil passage includes a first channel inside the penetrating portion and a second channel connecting the first channel and the bearing.

A drive apparatus includes: a motor having a shaft; a bearing rotatably supporting the shaft; a housing for the motor and holding the bearing in a bearing holding portion; an insulating member between the bearing and the bearing holding portion; and an oil passage. The bearing holding portion includes a holding tubular portion holding the bearing from radially outside, and a holding bottom portion extending radially inward from an end on one side in the axial direction of the holding tubular portion. The insulating member includes an insulating tubular portion extending in the axial direction along the holding tubular portion, and an insulating bottom portion extending in the radial direction along the holding bottom portion. The holding tubular portion has a penetrating portion penetrating radially inside and outside. The oil passage includes a first channel inside the penetrating portion and a second channel connecting the first channel and the bearing.

A structure for injecting cooling oil includes a motor having a stator core and coils wound on the stator core and protruding from the stator core and extending obliquely in an axial direction of the stator core; a first cooling pipe mounted at a first side of the motor and having a first injection hole to inject oil onto the coils therethrough; and a second cooling pipe mounted at a second side of the motor and having a second injection hole injecting oil into the coils, wherein the first injection hole injects oil onto portions of the coils extending obliquely outwards from the stator core in a direction moving away from the first injection hole and the second injection hole injects oil onto portions of the coils extending obliquely toward the stator core in a direction moving away from the second injection hole.

A structure for injecting cooling oil includes a motor having a stator core and coils wound on the stator core and protruding from the stator core and extending obliquely in an axial direction of the stator core; a first cooling pipe mounted at a first side of the motor and having a first injection hole to inject oil onto the coils therethrough; and a second cooling pipe mounted at a second side of the motor and having a second injection hole injecting oil into the coils, wherein the first injection hole injects oil onto portions of the coils extending obliquely outwards from the stator core in a direction moving away from the first injection hole and the second injection hole injects oil onto portions of the coils extending obliquely toward the stator core in a direction moving away from the second injection hole.

Systems for removing excess coolant oil and air from a radial air gap between a stator and a rotor of an electric motor are provided. In one example, the systems may include a ring covering the radial air gap, the ring configured to route coolant out of the radial air gap via one or more channels.

Systems for removing excess coolant oil and air from a radial air gap between a stator and a rotor of an electric motor are provided. In one example, the systems may include a ring covering the radial air gap, the ring configured to route coolant out of the radial air gap via one or more channels.

One embodiment is an electric drive system for an aircraft comprising a plurality of redundant motors, wherein power generated by the plurality of motors is used to drive a rotor system comprising a rotor shaft having a plurality of rotor blades connected thereto; a gear box associated with the plurality of redundant motors; a collective actuator for controlling a collective pitch of the rotor blades connected to the rotor shaft; and at least one structural element for retaining the redundant motors, the gear box, and the collective actuator together as a single integrated unit.

One embodiment is an electric drive system for an aircraft comprising a plurality of redundant motors, wherein power generated by the plurality of motors is used to drive a rotor system comprising a rotor shaft having a plurality of rotor blades connected thereto; a gear box associated with the plurality of redundant motors; a collective actuator for controlling a collective pitch of the rotor blades connected to the rotor shaft; and at least one structural element for retaining the redundant motors, the gear box, and the collective actuator together as a single integrated unit.

A method for manufacturing a stator for an electric machine comprises manufacturing a slot cooling fin to extend into a slot defined between a first tooth, a second tooth, and a stator yoke, and disposing a coil in the slot, wherein the slot cooling fin extends into the first coil.