Patent GB-966200-A (GB)
Title: Material conveyor apparatus
IPC: G05D9/12
Filed: 1962-07-26
Abstract: 966,200. Automatic control of conveyers. BROOKHURST IGRANIC Ltd. July 26, 1962 [Sept.13, 1961], No.28735/62. Heading G3R. [Also in Division H2]  Relates to sintering plant in which material is discharged from an incoming conveyer on to a dispensing conveyer which is provided with a cutoff plate to limit the depth of material dispensed thereby. A motor DM driving the dispensing conveyer is controlled in accordance with a first signal proportional to the weight of material delivered per unit of time, and a second signal proportional to the height of the pile of material in front of the cut-off plate. The signals are mixed in selected ratios to maintain the height of the pile at a normal level. The motor DM is supplied from a threephase magnetic amplifier PSX through rectifier RB2, an amplifier LSX controlling the signal level applied to the three-phase power amplifier. A pre-amplifier PRSX controls the amplifier LSX, and a pair of mixing amplifiers comprising speedup amplifier SUSX and slow-down amplifier SDSX control the reference winding of the pre-amplifier in an automatic manner. Alternatively, the preamplifier reference winding may be controlled manually. The bias winding of the amplifier SUSX is connected to rheostat RH11 to regulate the height of the pile relative to probes P1-P6. Reference winding SUPR is energized by a signal controlled by probes P1-P3 whilst winding SUSR is energized from load cell LC associated with tachometer generator 10 affording a signal proportional to the rate of delivery of material. Reference winding SDPR of amplifier SDSX is not energized except when the material rises above the normal level and engages one or more probes P4-P6. Reference winding SDTR is energized from tachometer generator 18 when the dispensing conveyer is running. Switches TA1-TA6 are used for testing the system in the absence of material embedding the probes. The system may be controlled from local or remote stations. A controller TMC is connected to the reference winding REF of pre-amplifier PRSX and comprises rate action, proportional action, and reset action circuits. The controller TMC is constructed so that, when it has no input signal, the motor is driven at a predetermined speed which is lower than that required to carry away material as fast as it is deposited on the dispensing conveyer. A feed back signal is applied to amplifier PRSX for this purpose. When the material embeds the measuring probe P4, winding SDPR is energized to increase the speed of the dispensing conveyer and to decrease the pile height to the normal level, winding SDTR providing speed stabilization. The rise in the height of the pile may be accompanied by an increase of the rate of delivery of material by the incoming conveyer. Such increase causes load cell LC to energize winding SUSR to contribute to the incremental change of motor speed. A rheostat RH11 in series with the bias winding of the amplifier SUSX allows the pile height to be adjusted. Adjustment of the cut-off plate is accompanied by resetting of compensator rheostats and potentiometer to change the motor speed. Means are provided to prevent change of motor speed when transferring from automatic to manual operation.