SE319237B - - Google Patents

Abstract

1,180,649. Electromagnetic switches. ALLMANNA SVENSKA ELEKTRISKA A.B. 2 June, 1967 [3 June, 1966], No. 25565/67. Heading H1N. [Also in Division F2] A time-delay relay with a latched armature comprises a synchronous motor which is energized at the same time as the relay winding and after a preselectable time interval releases the latching device to allow the armature to be fully attracted. A motor 1 drives a gear train 3 which can be selectively coupled to a shaft 13 by a tumbler gear 30 (see Division F2) which is axially slidable by rotation of an Archimedean screw 41. A clutch 18, 19, normally out of engagement, can couple shaft 13 to a differential gear assembly 7, 8, 9, the planet wheel 9 of which is carried on a disc 10 having an indicator arm 55 and a projection 16 which can engage a lug 51 to operate a pivoted latch 53. The time delay is selected by setting a pointer 12 against a scale 14 and by rotating the gear-change control 43 with a screwdriver to give a scale factor shown in a suitable window by disc 45. Crown wheel 8 is normally held against a stop (not shown) by a spring 11. Rotation of pointer 12 turns crown wheel 7 and hence moves planet wheel 9 (and disc 10) half as much, this being indicated on a shorter scale 56 by the arm 55. On energizing the relay coil (46, Fig. 4, not shown), its armature (28) is partially attracted against latch 53 and allows a spring blade (22, Fig. 2, not shown) to engage the clutch 18, 19. Motor 1 now drives crown wheel 8 to return the planet wheel 9 back to its initial position, tensioning spring 11 in the process. When arm 55 reads zero projection 16 engages lug 51 and the latch 53 is thereby removed from the relay armature which moves to its fully attracted position and switches off motor 1. When the relay coil is de-energized the armature disengages clutch 18, 19 and the spring 11 returns crown wheel 8, thus restoring planet wheel 9 to its set interval position in readiness for another cycle. Should the motor 1 overrun when the latch 53 allows the armature to fully attract, the projection 16 urges lug 51 beyond the release position and a further lug (54, Fig. 4, not shown) causes the clutch 18, 19 to disengage to prevent damage.