| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter capable of highly accurately measuring the quantity of flow by excluding the effects of electromagnetic noise. SOLUTION: Ultrasonic waves are transmitted and received in the forward direction and the backward direction of the flow of a fluid between a pair of ultrasonic oscillators 2 and 3 arranged at a prescribed distance from each other on the upstream side and the downstream side of a fluid conduit 1 through which the fluid flows in the ultrasonic flowmeter, and the ultrasonic flowmeter computes the quantity of flow on the basis of the difference in the time of arrival of the ultrasonic waves in each direction. The ultrasonic flowmeter is provided with a drive part 5 for driving a transmission-side ultrasonic oscillator; an amplification part 6 for amplifying signals outputted from a reception-side ultrasonic oscillator which has received ultrasonic waves from the transmission-side ultrasonic oscillator driven by the drive part 5; a time measuring part 7 for measuring the time to the reception-side ultrasonic oscillator's reception of ultrasonic waves transmitted from the transmission-side ultrasonic oscillator; and an operation part 8 for computing the quantity of flow on the basis of the time measured at the time measuring part 7. The amplification part 6 comprises a differential amplifier for differentially amplifying a group of signals each outputted from the pair of ultrasonic oscillators 2 and 3. COPYRIGHT: (C)2008,JPO&INPIT
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