Encapsulated motor with precision bearing registration

摘要

The rotor of an electrical motor, such as a hybrid permanent magnet stepping motor or a variable reluctance motor is assembled on a rotor shaft, and includes at least one lamination stack and a pair of supporting bearings, with the outer diameter of the bearings being slightly larger than that of the lamination stack. A stator is assembled from a stator lamination stack including a pole configuration and a pair of unmachined end caps registered and secured to the lamination stack such as by thru bolts. The registered stator assembly is potted to unitize the assembly, fixing the relationship between the end caps and the lamination stack, and providing a smooth continuous bore through the center of the stator assembly. The thus potted assembly is machined as by diamond lapping to form a continuous bore accurately machined through the center of the stator, concurrently forming bearing surfaces in the end caps and an intermediate machined section in the lamination stack. The rotor assembly is inserted into the stator assembly, with the machined bore providing bearing mounting surfaces in the end caps and an air gap for rotation of the rotor in the lamination stack.