| 摘要 |
PURPOSE:To provide a flow rate control unit of a variable speed fan using a detector without a differential pressure generator in a flow rate measurement by adjusting the opening degree of a fan inlet damper, holding the discharge pressure of the fan at a predetermined value to obtain the discharge flow rate of the fan, and actuating the device for driving the fan at a variable speed so as to set a discahrge flow rate to a predetermined value. CONSTITUTION:A discharge pressure adjusting meter 7 compares a signal proportional to a discharge pressure with a pressure set value of a fan discharge pressure setter 6, adjusts and computes, and a fan inlet damper operator 3 is controlled by an adjusting output so that the fan discharge pressure constantly assumes a predetermined value. A rotational speed generator 8 sends a signal proportional to the rotational speed thereof to a function generator 9. The function generator 9 outputs an air flow rate signal corresponding to the magnitude of the rotational speed of the fan to an air flow adjusting meter 11. The air flow adjusting meter 11 compares the air flow rate signal with an air flow rate instruction value 10 transmitted from other control system, adjusts and computes the same, and controls the rotational speed of the fan 1 through a fan speed variable drive device 2 thereby to adjust the rotational speed of the fan, that is, the discharge flow rate of the fan. |
