Stepping motor for clock movement - has two multi-polar rotor discs of soft magnetic material about single stator to overcome axial reaction

摘要

The rotor (2) of the motor is made with two multi-polar discs (7,8) which are magnetised and situated symmetrically about a stator (1). The discs (7,8) are fixed on a shaft (9) extending in the free space between the poles (10) of the stator and forming a pivot at either end. The shaft (9) limits axial movement by using shoulder sections (16), placed at each end, which are susceptible to come into contact with the end plates between which the shaft (9) is mounted. Each of the discs (7,8) bears a magnetic disc (13,14), which is made from a soft magnetic material, on its face which opposes the stator (2). A flywheel is also mounted on the shaft (9). The stator (2) is formed from two parts (3,4) which are connected in a bridge (5) bearing an excitation coil (6). The two discs (7,8) on the rotor suppresses the axial reaction which is encountered when only one disc is used.