Magnet retention in exterior rotor electric machines

1 . An electric machine of a gas-turbine engine having a longitudinal axis, the electric machine comprising:

a stator;

a rotor configured to rotate around the stator and about the longitudinal axis of the gas-turbine engine, the rotor comprising:

a rotor body having an inner surface and an outer surface; and

magnets on the inner surface of the rotor body, wherein axial edges of the magnets perpendicular to the longitudinal axis are shaped to include a shoulder that corresponds to a geometry of a radial retention structure of the rotor.

2 . The electric machine of claim 1 , wherein at least a portion of the radial retention structure is formed in the rotor body.

3 . The electric machine of claim 1 , wherein the rotor further comprises one or more retention rings attached to the rotor body and configured to radially retain the magnets to the inner surface of the rotor body, and wherein the one or more retention rings form at least a portion of the radial retention structure.

4 . The electric machine of claim 1 , wherein a radially inner surface of the magnets is substantially co-planar with a radially inner surface of the radial retention structure.

5 . The electric machine of claim 1 , wherein the magnets are attached to the rotor body.

6 . The electric machine of claim 5 , wherein, when attachment of a particular magnet of the magnets to the rotor body is intact, there is a gap between the particular magnet and a portion of the radial retention structure.

7 . The electric machine of claim 5 , wherein, when adhesive attachment of a particular magnet of the magnets to the rotor body has failed, the radial retention structure retains the particular magnet in the rotor.

8 . The electric machine of claim 1 , wherein a geometry of at least one axial edge of the axial edges of the magnets is shaped to include an L shape.

9 . The electric machine of claim 1 , wherein a geometry of at least one axial edge of the axial edges of the magnets is shaped to include a wedge shape.

10 . The electric machine of claim 1 , wherein the gas-turbine engine comprises:

a core section comprising at least one compressor and at least one turbine that both rotate about the longitudinal axis of the gas-turbine engine;

a core vane assembly coupled to the core section, wherein the core vane assembly comprises a plurality of core vanes configured to modify core fluid flow; and

a fan connected to the core section and configured to be rotated by the at least one turbine, rotation of the fan providing thrust to a vehicle that includes the turbine engine,

wherein the electric machine is integrated into the core vane assembly and positioned in the core section aft of the fan and fore of the at least one compressor, and

wherein the rotor rotates about the longitudinal axis.

11 . An electric machine of a gas-turbine engine having a longitudinal axis, the electric machine comprising:

a stator;

a rotor configured to rotate around the stator and about the longitudinal axis of the gas-turbine engine, the rotor comprising:

a rotor body having an inner surface and an outer surface; and

magnets on the inner surface of the rotor body, wherein axial edges of the magnets perpendicular to the longitudinal axis are profiled to include a shoulder that corresponds to a geometry of a radial retention structure of the rotor, wherein the magnets are attached to the rotor body, and wherein, when attachment of a particular magnet of the magnets to the rotor body is intact, there is a gap between the particular magnet and a portion of the radial retention structure.