Stepper motor with integrated threaded driving assembly

摘要

A stepper motor of the permanent-magnet sheet-metal type is constructed of a number of modules, simplifying assembly. The modular parts include a stator (28) having integrally-moulded winding bobbins and pole pieces. A rotor (30) mounted in the stator includes a barrier member which separates a plastic, threaded hub moulded interiorly from a permanent magnet moulded exteriorly. A shaft (22) having a first threaded end (66) rotatably engaged with the interior of the rotor hub has a rectangular central portion extending through a rectangular opening of the stator to convert rotary motion of the rotor to linear motion of the shaft. An opposite end of the shaft includes a moulded head (70b) and a tubular shield (72) extending from the head. This shield and a tubular portion of the stator moulding define a labyrinthal passage which inhibits the passage of contaminants into the rotor. A housing of the motor and a rotatably attached flange (24) include engagable portions to lock the flange at a desired angular position.