FLOW RATE MEASURING APPARATUS FOR FLUID MEDIUM

PROBLEM TO BE SOLVED: To obtain a flow rate measuring apparatus in which the circuitry for regulating the temperature of a heating circuit can be eliminated without sacrifice of accuracy or reliability at the time of evaluation by an arrangement wherein a heating voltage is constant or partially constant, a measuring voltage is evaluated using at least one characteristic curve, and the characteristic curve determines the relation between the measuring voltage and the flow rate of fluid. SOLUTION: A heating resistor RH heats at least one temperature dependent resistor and a resistor, being cooled differently by a fluid medium, is connected in a bridge DT such that the diagonal voltage thereof depends on the temperature difference of respective resistors. A following evaluation unit detects the quantity of fluid medium base on the diagonal voltage thus formed. The heating resistor RH is heated using a constant or partially constant heating voltage and the quantity of fluid medium is detected from a measuring voltage being fed to the heating resistor while taking account of a special curve determining the relation between the measuring voltage and the quantity of fluid medium.