Stepper motor with stator-rotor gear coupling - has bellows spring coupling between rotor and drive shaft to damp irregularities

摘要

The modification to a stepper motor with a wobble plate rotor is intended to damp out irregularities in the drive caused by meshing of the rotor and stator teeth. The stator (1) with its magnet poles (2) and windings (3) has a ring of teeth (4). The rotor (6) has a corresponding ring of teeth (5), and there is a difference of at least one tooth between the two rings. As the stator poles are successively energised the rotor is drawn axially towards the stator at the point of the magnetised pole. The tooth difference at meshing then imparts motion to the rotor. The rotor is mounted on a self-aligning bearing (8) and is coupled to the drive shaft (10) by a spring bellows (11). This has a high torsional stiffness and a constant angular spring constant around its perimeter. It acts as a damper to give more accurate angular movement of the drive shaft.