Rotor for an electric motor including a structure for retaining rotor segments and permanent magnets on a hub thereof

A rotor for an electric motor, the rotor comprising:

• a hub having a central axis;
• a plurality of rotor segments arranged around the hub;
• a plurality of permanent magnets;
• and
• an assembly for retaining the segments on the hub,
• wherein the assembly includes a plurality of rods which extend in an axial direction so as to retain respective rotor segments,
• the segments are arranged around the hub to define at least two rings, which are adjacent to each other in the axial direction,
• the rotor includes an intermediate plate between each ring of segments, wherein the rods pass through each intermediate plate,
• wherein the magnets and the hub are shaped so as to engage with each other in such a way that the hub restrains the magnets in the circumferential direction, with each magnet received by and in direct engagement with a parallel-sided groove defined by an outer circumferential surface of the hub, and the intermediate plate between each ring of segments defines a series of inwardly directed projections in engagement with the grooves in the hub in such a way as to resist rotation of the intermediate plate between each ring of segments around the axis of the hub.