Method of fixing unmagnetized magnetizable members to a rotor disc and a rotor disc

摘要

A rotor disc assembly 10 for an AC machine includes a rotor disc 20, permanent magnets 30 and a spider 40. The rotor disc 10 has a circumferential lip 22 projecting from a surface thereof. The permanent magnets 30 are positioned in a circular array on the surface of the rotor disc 20, with constant angular pitch, and so as to lie against the lip 22. The spider includes an annular base portion 41, with a plurality of arms 42 projecting radially outwards therefrom. The spider 40 is fixed to the surface of the rotor disc 20 such that each arm 42 is between and abuts a respective juxtaposed pair of the permanent magnets 30. The arms 42 and the members 30 are each provided with cooperating wedge-shaped cross sections such that each arm 42 constrains the respective two permanent magnets 30 both axially and tangentially on the surface of the rotor disc 20.