Patent ID: 7918238
Filing Date: 2011-04-05
Classification: G01F,G05D,Y10T

Abstract:
1. A flow control device for controlling a flow of a fluid in a channel in which the fluid is supplied to a target where a pressure is lower than a fluid supply source, comprising: a first opening and closing valve for opening and closing the channel; a flow control component with a flow control valve mechanism that controls the flow of the fluid flowing through the channel by adjusting an aperture of the flow control valve mechanism, the flow control component including a flow detector generating a flow detection signal indicative of a flow rate of fluid through the flow control component; an accumulator in which the fluid flowing through the channel can be held between the first opening and closing valve and the flow control component; a pressure detector disposed upstream of the flow control component, the pressure detector configured to generate a pressure detection signal indicative of the pressure of the fluid in the channel; and a control system for controlling operation of the flow control device, the control system receiving the flow detection signal and the pressure detection signal; the control system having a normal operating mode in which the first opening and closing valve is open and the control system adjusts a valve drive signal so that the aperture has an opening size dynamically selected to regulate a mass flow rate based on a target mass flow rate and the flow detection signal; the control system further having a test mode in which the first opening and closing valve is closed, the valve drive signal is set to fix an aperture size of the flow control valve mechanism during a measurement period and pressure change characteristics corresponding to decreases in pressure over time are monitored, wherein during the measurement period the pressure at the valve aperture is unregulated and a time-changing pressure at the aperture of the valve results in a non-constant flow rate of the fluid through the aperture; and the control system determining deviations from standard levels of predetermined standard pressure change characteristics associated with the aperture size used during the measurement period of the test mode to calibrate flow rates of the flow detector.