Patent GB-611923-A (GB)
Title: Improvements in or relating to temperature control means
IPC: G05D23/22
Filed: 1946-01-04
Abstract: 611,923. Automatic control systems for melting-vessels. POOL, W. Jan. 4, 1946, No. 380. [Class 38 (iv)] Temperature control.-In a melt-spinning apparatus for producing artificial filaments or the like, each unit of a battery of 12 electrically-heated vessels of the kind described in Specification 592,992 (Fig. 1, not shown), has a thermocouple giving an indication of its temperature. In the control mechanism 12, Figs. 3, 4, a motor-driven shaft 20 rotates an arm 16 carrying bridge pieces 17, 25, which respectively interconnect slip ring 18 with the 12- contact bank 21, and slip ring 26 with the 12-contact bank 27, the slip rings and contacts being mounted on insulating disc 19. The contacts of bank 21 are each connected to one side of the corresponding thermocouple (return leads being common) and the slip ring 18 to the input of the control instrument 11, Fig. 2 (not shown), which indicates the temperature of the thermocouple to which it is connected on a dial, and also (for example thermionically) closes or opens a relay in the A.C. supply from transformer 31 to slip ring 26 according as the temperature of the vessel presently under test is above or below an adjustable datum. The contacts 27 are respectively connected to a bank of 12 solenoids 28 (return leads common), each of which controls the heater switch of the corresponding melting vessel through its own mechanical operator. Energization of a solenoid lifts the associated lever 46 which controls the engagement of the driven member of clutch 35 with the driving member 36 which is fast to a shaft 20, and allows the two members to rotate together, while non-energization allows lever 46 to remain down, tripping lever 40 to disengage the clutch. The end 51 of a bell-crank 52 rests in a notch 50, while member 37 is stationary, and rides on the periphery of the member when it is in motion. The motion of the bell-crank tilts a hooked lever 64, about pivot 65,. which is laterally oscillated once in 15 seconds by lever 79 driven by rocker 78 engaged by a crank-pin 73 on a chain-driven sprocket 70 geared to shaft 20. The hooks alternatively drive a slidable notched insulating strip 58 in either lateral direction to operate the appropriate heater switch 56 in the on or off direction. Thus, each vessel temperature is cyclically tested and if below a fixed datum the appropriate solenoid is energized, member 37 rotates, bell-crank 52 tilts lever 64 and strip 58 is urged to switch on the appropriate heater for the ensuing cycle. If the temperature exceeds the datum, the solenoid is de-energized, clutch 35 is tripped, member 37 is stopped with its notch engaging the bell-crank, and lever 64 is tilted to urge strip 58 to switch off the appropriate heater. The cyclic testing process is continuous, completing itself in 3 minutes, and a pointer 84 is driven by sprocket 85 at the same speed as shaft 20 to indicate on a dial the vessel under instantaneous test. A lamp behind each dial member, illuminated through a switch 86, glows when power is supplied to the appropriate vessel heater. In a modification, the power switches may be operated directly by the solenoids, or by wedge-shaped projections on a continuously rotating drum which may be shifted axially, to engage or disengage a particular switch, by a single solenoid operable by the selector means.