GB607879A - Electric follow-up systems - Google Patents

Abstract

607,879. Electric follow-up systems. YARDENY, M. N. Sept. 21, 1945, No. 24523. [Class 40 (i)] In a positional correspondence control system involving a reversible electric servomotor controlled according to the relative position of the members of a two-way and off type switch, one member of the switch is so coupled to the servomotor that one revolution of a shaft driven by the servomotor corresponds to a fraction of the maximum displacement of the switch members, the shaft operating a switch only during the major portion of one revolution upon reversal of the servomotor to slow down the servomotor. A movable load member 61 is driven through gearing 56, 57 by a reversible induction motor 1 to a position dependent on the setting, through transmission 20, 21 of a rotary ball-shaped contact 24 relative to rotary conducting segments 25, 26 separated by an insulating gap 30 and driven through gearing 56, 57, 79, 59 by motor 1. When the setting of contact 24 is such that it engages segment 25 or 26, relay 36 or 37 is respectively energized from a source 15 to complete the circuit to winding 2 or 3 of motor 1 which then drives load 61 and segments 25 and 26 in the appropriate direction until contact 24 lies within or bridges gap 30. The following anti-hunting features are described : (a) A fly-wheel 64 coupled to the shaft of motor 1 through an adjustable friction clutch 65 to retard the motor when it reverses on contact 24 overrunning gap 30. (b) Increased radius of segments 25 and 26 in the proximity of gap 30, Fig. 5 (not shown), to increase resistance to movement of contact 24 when the latter is in the neutral position. (c) Introduction, in the drive from gear 57, of a lost-motion coupling, Fig. 3 (not shown), which is normally locked by a friction coupling. The increased resistance referred to at (b) above is, however, sufficient to overcome the friction coupling so that a limited idle movement of gear 57 occurs when contact 24 reaches the neutral position. Gear 57 may be a pair of spring-coupled gears initially set to take up play in the drive from worm 56. (d) A onerevolution lost-motion device 11 which, when motor 1 reverses on contact 24 overrunning gap 30, removes a short-circuit from relay 6 which then vibrates to interrupt, periodically, the motor circuit and give slow speed final adjustment. Manual means, Figs. 1 and 3 (not shown), are provided for adjustment of load member 61 and segments 25 and 26 without rotating motor 1. In Fig. 4 (not shown) two separate pairs of rotary segments have their associated contacts adjusted to different positions and a single D.C. shunt motor drives the load member into correspondence with one or the other according to which of two switches .is closed. In this arrangement the lost-motion device corresponding to that at (d) above introduces a resistor into the armature circuit when it operates.