PURPOSE: To improve stability and quick responsiveness by preventing flow overshoot at the time of opening a valve in the case of flow feedback control using a flow sensor and a motor concerning the flow controller for supplying/ stopping fluid and adjusting flow.
CONSTITUTION: A duct provided with two entrances 18 and 19 and one exit 20 at velocity corresponding to set flow (a) at the time of opening the valve is equipped with two valve elements 22 and 24 linked to one valve shaft and at the central position of the valve shaft, any one of two valve elements is selectively opened corresponding to movement to right and left with the rotation of a motor 12 from the central position of the valve shaft. This device is provided with a valve opening time motor control part 31 to drive the motor 12 at the velocity corresponding to the set flow in the case of opening the valve until getting a flow signal at a flow calculation part 14. Therefore, the motor 12 is driven slowly at the time of small set flow, driven quickly at the time of large set flow and operated so as to prevent the overshoot of flow caused by the delay of flow detection at the time of reducing the set flow, and the control at the time of opening the valve can be stably performed in the shortest time corresponding to the set flow.
SHIRAI SHIGERU
KIDOUCHI YASUO
