Patent ID: 8903663
Filing Date: 2014-12-02
Classification: G01F

Abstract:
1. A flow measurement device comprising: a pair of vibrators being placed across a flow path for transmitting and receiving an ultrasonic wave between them to measure a flow rate of fluid flowing through the flow path; a transmission device that drives one of the vibrators to transmit an ultrasonic wave; a reception unit responsive to an output signal from the other of the vibrators to convert the output signal into an electric signal representing cycles of the ultrasonic wave propagated from the one of the vibrators; a reception wave determination unit that monitors the electric signal from the reception unit and outputs a detection signal when the wave in the cycles first becomes a predetermined value; a reception point detection unit that detects zero-crossing points of the cycles from the electric signal; a reception point storage that stores arrival times of at least two zero-crossing points detected by the reception point detection unit, wherein the stored arrival times comprise arrival times of adjacent zero-crossing points among a series of detected zero-crossing points starting from an earliest detected zero-crossing point through a last zero-crossing point detected immediately before the reception wave determination unit outputs the detection signal; and a flow rate computation unit that calculates the flow rate based on an average of the arrival times of adjacent zero-crossing points stored in the reception point storage.