Permanent magnetic motor for vehicle door window

Abstract From the Canadian patent

A dynamo-electric machine comprises an armature and a permanent magnet field structure including at least two permanent magnets and at least two field shoes. Each field shoe has an arcuate surface which forms one side of an air gap between the shoe and the armature and is, configured to direct magnetic flux from the permanent magnets to the arcuate surface such that the magnetic lines of force emanating from the surface and extending through the armature are of substantially uniform distribution and intensity. This is accomplished by making the shoe decrease from a maximum thickness in the radial direction in the area of the arcuate surface adjacent the magnets to a minimum thickness in the …