SMC IP5100-030 POSITIONER

When the input pressure applied to the SIG port of the positioner increases, bellows press balance lever to the left. As this movement moves flapper to the left through connecting spring, the gap between nozzle and flapper widens, and the nozzle back pressure of pilot valve drops. As a result, the pressure balance in the constant pressure chamber is broken, and exhaust valve presses inlet valve B to the right. Then, inlet port B opens, and output pressure OUT1 increases. In the meantime, the movement of exhaust valve to the right opens exhaust port A, and output pressure OUT2 decreases. Therefore, pressure difference is generated between pressure chamber 1 and pressure chamber 2 of oscillating actuator, and actuator shaft turns in the direction of the arrow. The movement of actuator shaft deflects feedback arm to the right through feedback shaft, cam, and bearing. Such deflection increases the tension of feedback spring and acts on balance lever.Since oscillating actuator moves until the tensile force of feedback spring nd the force generated by bellows balance, it is always set in the position proportional to the input pressure. When the signal air pressure decreases, the operation is reversed.