Electromotor, as the drive for a sewing machine arm shaft, has structured holders at the rotor body to hold the permanent magnets accurately in a magnetic orientation

摘要

The drive for the shaft in a sewing machine arm is an electromotor (12), with a rotor (40) and a stator (33). The rotor, keyed to the arm shaft, has a rotor body (42) and a number of permanent magnets (46), within shaped holders (42-45), each in an asymmetric shape so that each magnet is held accurately in a magnetic orientation. Each holder has a projection (51) to fit within a groove at the base of each magnet.