preselector for controlling the with variable time intervals, which takes place stepwise advance of control cam of a cam disks block

摘要

1,194,208. Time switches. CROUZET. 18 July, 1967 [22 July, 1966; 14 Nov., 1966], No. 32850/67. Heading H1N. A programming cam assembly is stepped at different time intervals by intermittent engagement with a continuous drive when an electromagnet is pulsed to engage a toothed clutch, pulses at different frequencies being provided by the same continuous drive and selected automatically by a cam or cams on the stepping assembly itself. Shaft 7, geared from a synchronous motor (not shown), drives gear-wheels 8, 11 to rotate a sleeve 10 having fingers 10a which are slidingly engaged by a wheel 12 attached to a slidable core 13 of a solenoid 5. An energizing pulse applied to winding 5 thus engages teeth 12a with teeth 6a to step a cam assembly 6 which is rotatable on a fixed shaft 3. The stepping positions are located by teeth on a spring-urged crown B co-operating with those on a fixed ring A. A cam wheel 15 has teeth 15a engaged by a wheel 16 integral with wheel 8 but differing in diameter such that wheel 15 is driven at a somewhat greater speed than sleeve 10 and wheel 12. Impulses are provided by a movable contact (17, Fig. 2, not shown) operated to engage alternative fixed contacts by a projection 15b and a notch 15c on the periphery of wheel 15, but the notch 15c is initially obturated (Fig. 2, not shown) by a vane 20 rotated with wheel 12 by the mutual engagement of teeth 20b and 12b. Thus notch 15c is uncovered (Fig. 3, not shown) only after wheel 15 has made a predetermined number of revolutions depending upon the difference in speed of wheels 12 and 15, and the extent of vane 20. Each time wheel 12 is attracted by solenoid 5 it disengages teeth 20b, 12b and a spring 21 returns the vane 20 to its initial obturating position. Thus the two fixed contacts (18, 19, Fig. 2, not shown) are periodically engaged at two different respective time intervals. A cam 6b of assembly 6 actuates a change-over contact to decide which pulsing contact (18 or 19) is connected to the solenoid 5. A third series of pulses may be provided by further contacts operated by a further notch 15SP1/SPc obturated (Fig. 4, not shown) by a larger vane 20SP1/SP, and a cam 6c may be used to select this time interval. In a modification (Fig. 6, not shown), to ensure that the pulse is not too short to produce a step of assembly 6, the vane 20 is allowed some axial movement to follow wheel 12 so that it does not restore the pulsing contact (17) on returning to its obturating condition.