PURPOSE:To accurately measure the flow rate of a fluid regardless of the temperature change of the fluid by finding a measurement error at a predetermined flow rate from storage tables respectively indicating the relations between previously measured inter-coil voltages and the temperature of the fluid and between the temperature of the fluid and measurement errors. CONSTITUTION:A first storage table indicating the relation between the inter-coil voltage of an exciting coil 2 and the temperature of a fluid to be measured and second storage table indicating the relation between the temperature of the fluid when the flow rate of the fluid is 100% and measurement errors of signal electromotive forces are prepared from measured results and stored in an EEPROM 12. An electromotive force detecting circuit 6 detects the signal electromotive force between electrodes 4a and 4b and a CPU 9 finds measured values based on the electromotive force. At the time of finding the electromotive force, the CPU 9 fetches the inter-coil voltage of the coil 2 and reads out the fluid temperature corresponding to the voltage from the first storage table in the ROM 12 and the measurement error when the flow rate is 100% at the fluid temperature from the second storage table. Then the CPU 9 finds the measured flow rate value of the fluid which is not affected by the temperature change of the fluid by calculating and eliminating the measurement error contained in the signal electromotive force based on the read-out measurement error.
【目的】 流体温度の変化とは無関係に正確に流量測定 を行う。
【構成】 周期的に励磁電流Ｉ EX の供給が中断される直 前の励磁コイル２のコイル間電圧Ｅ x を検出する。この 検出したコイル間電圧Ｅ x に対応する流体温度Ｔ x を第 １の記憶テーブルから読み出す。この読み出した流体温 度Ｔ x での１００％流量時における計測誤差Ｎ x(100) を 第２の記憶テーブルから読み出す。この読み出した計測 誤差Ｎ x(100) に基づき、信号起電力の検出値ｅ x(y) に含 まれている計測誤差Ｎ x(y) を算出し、この計測誤差Ｎ x(y) を信号起電力ｅ x(y) から除去する。