Electric machine—over-moulding construction

A method of constructing an electric machine of the type comprising a rotor having permanent magnets and a stator having coils wound on stator bars for interaction with the magnets across an air gap defined between them, wherein the bars and coils thereon are enclosed by an annular stator housing, the method comprising the steps of:

• a) providing a first mould;
• b) disposing first shoes of the stator bars in the first mould;
• c) closing the first mould and injecting molten reinforced plastics material into the first mould;
• d) opening the first mould after cooling and ejecting a first clamshell in which said first shoes are retained in the plastics moulded material of the first clamshell;
• e) providing a second mould;
• f) disposing second shoes of the stator bars in the second mould;
• g) closing the second mould and injecting molten reinforced plastics material into the second mould;
• h) opening the second mould after cooling and ejecting a second clamshell in which said second shoes are retained in the plastics moulded material of the second clamshell;
• i) wherein the first and second clamshells are each formed with cylindrical wall parts on inner and outer radii and a radial wall joining the inner and outer cylindrical wall parts;
• j) mounting stator coils on the stator bars;
• k) connecting together facing edges of said inner and outer cylindrical wall parts of the first and second clamshell housings to form said stator housing, whereby respective first and second stator shoes of each clamshell housing are mated together, securing the stator coils therebetween;
• and
• l) assembling the stator housing with the rotor.