GB1051182A - - Google Patents

Abstract

1,051,182. Synchronous motors. INDIANA GENERAL CORPORATION. June 5, 1963, No. 22419/63. Heading H2A. A synchronous A.C. motor such as for a clock or timing device comprises a stator having an annular permanent magnet 160 concentric with a central axis and at least one of whose radially spaced inner and outer peripheral surfaces has a plurality of axially extending circumferentially spaced successively opposite polarity magnetized poles, a low inertia cup-shaped rotor 140 rotatable about the axis and having transverse to the axis a central portion 142 from which extend parallel to the axis a plurality of magnetizable salient polepieces 151 . . . 158 adjacent the permanently magnetized poles, and fixed to the stator an A.C. field winding 113 which when connected to an A.C. source 170 induces alternating magnetic poles of the same instantaneous polarity in all the salient polepieces 151 . . . 158 adjacent the same peripheral surface of the magnet whereby the rotor is driven in synchronism with the A.C. voltage. In the embodiment shown the rotor hub 140a is pressed fitted to a shaft 141 rotatable in a bore 111c in a magnetic core 111, but in the other embodiment, Figs. 3 and 4 (not shown), the rotor hub rotates on a stationary bearing pin and the rotor includes a further set of polepieces outside the magnet and fixed to the first set by a non-magnetic disc. The magnet may be a ceramic such as unoriented barium ferrite. Means may be provided to prevent reverse rotation.