| 摘要 |
PROBLEM TO BE SOLVED: To precisely measure a flow rate value with a reduced measuring frequency, even when a flow rate of a measuring object is fluctuated by fluctuation of pressure or the like. SOLUTION: A cycle measuring period and a flow rate measuring period are provided in measurement by a flowmeter, a fluctuation widthΔh of a propagation time h<SB>fj</SB>between a transmission sensor and a reception sensor, and a distortion related value h<SB>v</SB>of a fluctuation cycle h<SB>f</SB>of the propagation time are found in the cycle measuring period, those are compared with a prescribed fluctuation width allowance value h<SB>0</SB>and a prescribed distortion related allowance value h<SB>v0</SB>to be classified into A (low fluctuation), B (sine wave fluctuation) and C (distorted wave fluctuation), and a measuring time interval t<SB>T</SB>for measuring an ultrasonic flow rate in the flow rate measuring period is changed based on the classification to measure the flow rate. COPYRIGHT: (C)2005,JPO&NCIPI
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