Combined motor and relay electric timing device

摘要

1,016,355. Switches, partly electromagnetic. GENERAL TIME CORPORATION. April 4, 1963 [Aug. 24, 1962], No. 13508/63. Heading H2B. A device for connecting a supply to a load after a predetermined time interval from closure of an initiating switch comprises a relay 11, Figs. 1 and 2 (not shown), having contacts 26, 27 in the load circuit and holding contacts 22, 23 in the circuit of its winding 16, combined with a synchronous motor 12 arranged to drive a cam 30 until it closes the relay holding contacts 22, 23 by direct mechanical engagement with follower 35 mounted on contact spring 21 as shown. Contact 23 is connected to main supply by closure of an external initiating switch (Fig. 4, not shown), and motor 12 is energized over contact 21, causing its armature to move axially and thereby engaging gearing (Fig. 3, not shown) to drive cam 30 clockwise against the tension of a spiral spring 52. When cam 30 engages follower 35 contacts 22, 23 are closed and winding 16 is energized to attract armature 17, thereby maintaining contacts 22, 23 closed and separating contacts 21, 23. This de-energizes the motor 12, its armature is spring-urged out of engagement with the gearing to cam 30 which returns under action of spring 52 to its rest position (Fig. 1, not shown) wherein a lug 50 abuts a stop 51. The relay also maintains its contacts 26, 27 in the load circuit closed until the initiating switch is opened to remove the main supply from contact 23. Cam 30 is adjustably secured to drive shaft 32 by a nut 55 to provide variation of the time delay. In an alternative embodiment, not illustrated, the restoring spring 52 and stop 50, 51 are not provided and the cam is arranged to pass beyond the follower 35 due to momentum of the motor after switch-off, it then being in readiness for a subsequent cycle. In this case the motor speed and gear ratio is chosen such that the desired time delay corresponds to one full revolution of the cam.