CLOSED LOOP SPEED CONTROL CIRCUIT FOR OIL PRESSURE ACTUATOR

摘要

PURPOSE:To prevent a deterioration of stableness of the closed loop speed control circuit for oil pressure actuator by incorporating one of a pair of electromagnetic proportional flow rate control valves in a closed loop and the other in an open loop. CONSTITUTION:A sum of operating oil passing through the pair of electromagnetic proportional flow rate control valves 14 and 15 determines the moving speed of an oil pressure cylinder 11. The former of the control valves is incorporated in the speed closed loop and the latter in the open loop. A comparator 20 compares a value detected by a speed detector 18 with the value preset by a speed setting device 19 and provides outputs. A driving circuit 22 receives a signal outputted from an operation circuit 21 and amplifiers the signal to control a first valve 14 thereby. A driving circuit 23 controls a second valve 15. Thus the stableness of the closed loop speed control circuit for the oil pressure actuator is prevented effectively from deterioration.