Importance

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Abstract

A stator having a plurality of permanent magnets with a cylindrically shaped outer surface and with at least one planar opposite surface is manufactured to close tolerances of the air gap with the aid of a plurality of ferromagnetic link members, equal in number to the number of permanent magnets and adapted to come into planar contact with those surfaces of said permanent magnets which are pointing away from the air gap. The permanent magnets are placed into a cylindrically shaped sleeve, the inner diameter of which corresponds to the desired inner diameter of the air gap of the stator. A sleeve of a ferromagnetic material may be used for holding said permanent magnets in intimate contact with the sleeve. The link members are shaped so as to be brought into generally planar contact with at least part of the inner surface of two adjacent ones of the permanent magnets. An adhesive is used to secure the link members to the permanent magnets. The so formed permanent sub-assembly may be secured in an known manner to an end plate of the stator housing. A flux return ring is also secured to that end plate. The sleeve is withdrawn from said permanent magnets after the adhesive has cured and preferably after the permanent magnet subassembly has been fixed to the end plate. The sleeve may be formed so as to have an outer diameter corresponding to the outer diameter of the desired air gap. By this, a close toleranced air gap will be provided even if the individual permanent magnets are not formed for high tolerances.

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First Claim