VARIABLE SPEED RESISTIVE NETWORK FOR A PNEUMATIC SERVO ASSEMBLY OF AN ELECTRO-PNEUMATIC CONVERTER

摘要

The converter includes a reversible dc servo motor with a pair of terminals connected to a pair of lines. The lines are selectively connectable to a common terminal of a power supply. The power terminal of the power supply is connected over a variable resistor to a terminal connecting the lines. Selectively connecting one of the lines to the common terminal causes electrical power to pass through the motor and one for an opposite direction to turn the motor shaft in a selected direction of rotation. The speed of rotation is determined by the position of the variable resistor. The The motor shaft is used in conjunction with a cam that is associated with a nozzle supplied with pressurised gas over a bellows. The nozzle is moved closer or further away from the cam edge as the bellows expands or contracts. A line connected upstream of the bellows provides gas at a selected pressure which is proportional to the position of the cam.