| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter which ensures a fixed level of detection accuracy, as well as, achieves low-power consumption. Ž<P>SOLUTION: The ultrasonic flowmeter 1 is provided with a pair of ultrasonic transmitting/receiving elements 2a, 2b on the upstream and the downstream within a channel 3 flowing a fluid GF; repeatedly emits a measuring ultrasonic wave per a predetermined period T for flow rate measurement; controls an oscillating frequency at each reception of the measuring ultrasonic waves so that the measuring ultrasonic waves emitted next time comes to a lock the wavenumber determined previously between the pair of ultrasonic transmission/reception elements 2a, 2b; and obtains a flow velocity and a flow rate based on the oscillating frequency controlled within the period T for flow rate measurement. The emission time span of measuring ultrasonic waves at a period T for flow rate measurement is previously defined so that the side of measurement completion is shorter than the side of measurement initiation. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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