ULTRASONIC FLOWMETER AND FLOW RATE COMPUTATION METHOD

To enable an increase in current consumption to be avoided while maintaining measurement accuracy more than conventionally possible.SOLUTION: The present invention comprises: a received signal acquisition unit 401 for acquiring a received signal which is received by an ultrasonic sensor 2; a received signal acquisition unit 402 for acquiring a received signal which is received by an ultrasonic sensor 3; and a drive wavenumber control unit 407 for controlling the drive wavenumber of ultrasonic wave transmission by a pair of ultrasonic sensors 2, 3, on the basis of acquisition results by the received signal acquisition unit 401 and the received signal acquisition unit 402. When the drive wavenumber of ultrasonic wave transmission by the ultrasonic sensor 3 is increased by the drive wavenumber control unit 407, a zero-cross point measurement unit 403 measures the duration of the first-half zero-cross point and then, after temporarily stopping measurement, measures the duration of the latter-half zero-cross point. When the drive wavenumber of ultrasonic wave transmission by the ultrasonic sensor 2 is increased by the drive wavenumber control unit 407, a zero-cross point measurement unit 404 measures the duration of the first-half zero-cross point and then, after temporarily stopping measurement, measures the duration of the latter-half zero-cross point.SELECTED DRAWING: Figure 2 【課題】従来に対し、計測精度を維持しつつ、消費電流の増加を回避可能とする。【解決手段】超音波センサ２により受信された受信信号を取得する受信信号取得部４０１と、超音波センサ３により受信された受信信号を取得する受信信号取得部４０２と、受信信号取得部４０１及び受信信号取得部４０２による取得結果に基づいて、一対の超音波センサ２，３における超音波送信の駆動波数を制御する駆動波数制御部４０７とを備え、ゼロクロス点計測部４０３は、駆動波数制御部４０７により超音波センサ３における超音波送信の駆動波数が増加された場合、前半のゼロクロス点の時間計測を行った後、計測を一旦休止した後に、後半のゼロクロス点の時間計測を行い、ゼロクロス点計測部４０４は、駆動波数制御部４０７により超音波センサ２における超音波送信の駆動波数が増加された場合、前半のゼロクロス点の時間計測を行った後、計測を一旦休止した後に、後半のゼロクロス点の時間計測を行う。【選択図】図２