To obtain a highly sensitive, highly accurate, and stable flow detection with a simple structure and at a low cost.
A flow sensor is provided with both a tubular body A to convert the flow of a fluid (a) into a pressure difference ΔP between fluid pressures Pa and Pb through the use of an internally formed large-diameter channel part 3 and a small-diameter channel part 4 having different cross sectional areas and a pressure sensor B set in the peripheral wall 1a of the tubular body A. The pressure sensor B is provided with a diaphragm 11 to be displaced according to the pressure difference ΔP, a variable capacitor 12 to convert the displacements of the diaphragm 11 into changes in electrostatic capacitance, and a means to detect the changes in the electrostatic capacitance of the variable capacitor 12 and to compute the quantity of flow.
BINGO HIDEYUKI
NOZOE SATOSHI
