GB1352426A - Electrically driven timer device - Google Patents

Abstract

1352426 Magnetic couplings; motor driving arrangements SIEMENS AG 17 Aug 1971 [17 Aug 1970] 38609/71 Heading H2A [Also in Divisions G3 and H1] An electrically driven timer, e.g. a time switch comprises a mechanical oscillator 1 which is powered by D.C. and able to drive a gear train 6-8 via a magnetic coupling 4, 5; and a synchronous motor 13 which is releasably coupled to the gear train to drive the latter when the motor is energized. As shown, one tine of tuning fork 1 carries a permanent magnet 3 co-operating with a driving coil 2 which is powered by D.C. The other tine carries a U-shaped magnet 4 which embraces a wavy-track magnetic wheel 5 so that the latter is normally stepped around by the oscillating magnet 4. The wheel 5 carries a pinion 6 meshing with a gear 7 on a shaft 14, Fig. 2. A serrated iron wheel 9 is mounted on the shaft 14 by means of a clip 15 so as to revolve with the gear 7 but be capable of a small axial movement. An end 10 of shaft 12 of the motor 13 has magnetic poles around its periphery. -The motor is a sliding armature motor so that when it is energized to synchronize the timer with the mains, the shaft end 10 slides into engagement with the wheel 9 and is magnetically coupled thereto. Engagement is assisted by the conical shaft end and the wheel 9 is coated with plastics to present a smooth, unbroken surface. This coupling is stronger than that between the parts 4, 5 so that the gear train is driven by the motor 13, independently of the fork 1. A magnetic clutch 11 may alternatively be used. The gear train may be normally driven by the motor 13 in which case the oscillator 1 is powered by a battery which is charged from the mains and constitutes a standby supply in the event of mains failure.