| 摘要 |
PURPOSE:To automatically eliminate an overload condition of a motor by detecting an overcurrent of the motor, which controls a valve opening, supplying an output of the overcurrent to a capacitor in a lock circuit and full close-full open or full open-full close actuating a valve by a pulse signal when the capacitor exceeds predetermined voltage. CONSTITUTION:When a motor is stopped with foreign matter biting or the like halfway a rotary control of the motor 24 by changing a valve opening setting signal, an overcurrent is detected by an overcurrent detecting circuit 26. When the overcurrent is detected, for instance, for not less than several seconds, a lock detecting circuit 31, by voltage of a capacitor in the inside exceeding a predetermined value, generates an output to cut off the motor current, and the motor 24 is driven by a pulse of the first pulse generating circuit 32. Next a pulse is generated by the second pulse generating circuit 33. By this pulse, a valve 11 is full open-full close or full close-full open actuated to remove the caught foreign matter, and a valve opening is set to a preset value. Thus, any overload of the motor is automatically eliminated. |
