GB1017551A - - Google Patents

Abstract

1,017,551. Time switches. W. HOLZER. Nov. 12, 1962 [Nov. 30, 1961], No. 42684/62. Heading H2B. The contacts of a time switch are operated by the relatively small timing motor by means of a cam driven through gearing which is not part of the timing train and which is coupled and uncoupled to effect closing and opening of the contacts. A synchronous motor 1 drives an hour hand 15 via gear 13 slidably keyed on a hollow shaft 14, and a minute hand 16 via gear 10 and shaft 11. A spring 20 tends to urge gear 13 into engagement with a pinion 34 but is restrained by a lever 22 pivoted at 25 on a disc 26 rigid with shaft 14 and having one end 21 engaged in a groove 19 in the bushing of gear 13 while the other end 23 normally wipes over tracks 24 and 44 on setting discs 29 and 28, respectively. Tracks 24 and 44 extend mutually to cover 360 degrees (Fig. 2, not shown) and a pin 46 on disc 29 moves in an arcuate slot 45 in disc 28 such that rotation of disc 29 by means of knob 33 first in one direction and then the other adjusts the overlap of tracks 24 and 44 leaving a selected sector free of either track. As lever 22 is driven round the end 23 drops off track 24 at the preset " on " time and gear 13 is slid into mesh with pinion 34 to rotate cam 37 via gears 35, 36. Cam 37 winds a spiral spring 40 and after closing contacts 38, 39 engages an abutment pin 42 where it is held stationary against slip of a friction clutch 43. When end 23 of lever 22 rises on to track 44 at the preset "off " time the gear 13 is withdrawn from pinion 34 and the spring 40 restores cam 37, thereby opening contacts 38, 39. Abutment pin 42 also determines the rest position of cam 37 such that it has to cover a certain distance before closing the contacts; this ensures that the contacts are not operated by rapid movement of the discs through the switching position while setting them. Overlapping arcuate holes 48 (Fig. 2, not shown) in the discs 28 and 29 expose to view a further disc (not shown) with coloured or luminous time interval markings. In a modification (not illustrated) the lever 22 carries a member which engages the indicator disc to move it while the contacts are closed to shown the time left until switching off takes place. A time dial 49 is mounted between a transparent cover 17 and the discs 28, 29.