| 摘要 |
PURPOSE:To measure a flow velocity independently of a sound velocity and simplify a circuit construction by removing a sound velocity component from a differential signal, minimizing a quantity corresponding to an error between the output signal of multiplying means and a constant value and measuring the flow velocity from the differential signal of control signals. CONSTITUTION:Based on the outputs of ultrasonic wave transmitting and receiving means 1a and 1b arranged in prescribed positions on the upstream and downstream sides of a fluid to be measured, ultrasonic wave reaching times Ta and Tb when ultrasonic waves are radiated from upstream side to downstream side and vice versa, respectively, are outputted from ultrasonic wave reaching time detecting means 2. The times Ta and Tb are multiplied by control signals X and Y supplied from error detecting means 4 in multiplying means 3 and obtained signals Ta.X and Tb.Y are outputted, respectively. The means 4 outputs the signals X and Y corresponding to quantities corresponding to errors between the signals Ta.X and Tb.Y and a constant value K, respectively. The signals X and Y are fed back to the means 3 so that the quantities become minimum and supplied to differential signal output means 5 to output (5) a differential signal (X-Y) between the signals X and Y. A flow velocity is calculated from the differential signal. |
