ULTRASONIC FLOWMETER AND FLOW RATE MEASUREMENT METHOD

To enable instantaneous flow rate measurement to be performed more appropriately than before, even when an ultrasonic wave propagation time has suddenly changed.SOLUTION: The present invention comprises: a setup unit 1041 that sets a plurality of reception start groups for a plurality of isolated measurements that are included in a packet and sets reception start timings that are different for each of the reception start groups; a normal zero-cross point determination unit 1047 that determines, for each of the reception start groups which are set by the setup unit 1041, whether or not a measurement result is normal, on the basis of the results of measurements by a first zero-cross point measurement unit 1046-1 and the results of measurements by a second zero-cross point measurement unit 1046-2; a propagation time calculation unit 1048 that calculates, for each packet, the propagation time of an ultrasonic wave, on the basis of the results of measurements by the first zero-cross point measurement unit 1046-1, the results of measurements by the second zero-cross point measurement unit 1046-2, and the results of determination by the normal zero-cross point determination unit 1047; and a flow rate calculation unit 1049 that calculates, for each packet, the flow rate of a fluid to be measured, on the basis of the results of calculation by the propagation time calculation unit 1048.SELECTED DRAWING: Figure 2 【課題】従来に対し、超音波の伝搬時間が急変した場合でも、瞬時流量計測を適切に実施可能とする。【解決手段】パケットに含まれる複数の単計測に対し、複数の受信開始グループの設定、及び、当該受信開始グループ毎に異なる受信開始タイミングの設定を行う設定部１０４１と、第１のゼロクロス点計測部１０４６－１による計測結果、及び、第２のゼロクロス点計測部１０４６－２による計測結果に基づいて、設定部１０４１により設定された受信開始グループ毎に、計測結果が正常であるか否かを判定する正常ゼロクロス点判別部１０４７と、第１のゼロクロス点計測部１０４６－１による計測結果、第２のゼロクロス点計測部１０４６－２による計測結果、及び、正常ゼロクロス点判別部１０４７による判別結果に基づいて、パケット毎に、超音波の伝搬時間を算出する伝搬時間算出部１０４８と、伝搬時間算出部１０４８による算出結果に基づいて、パケット毎に、測定対象である流体の流量を算出する流量算出部１０４９とを備えた。【選択図】図２