| 摘要 |
PCT No. PCT/JP95/02142 Sec. 371 Date Apr. 18, 1997 Sec. 102(e) Date Apr. 18, 1997 PCT Filed Oct. 19, 1995 PCT Pub. No. WO96/12933 PCT Pub. Date Feb. 5, 1996An ultrasonic flow meter includes a conduit through which a fluid flows, an ultrasonic generator, a receiver for receiving ultrasonic waves on the upstream or downstream side of the generator, a time counter for determining the propagation time of the ultrasonic wave, a flow rate calculator for calculating the flow rate from the propagation time, and a timing controller. The timing controller sets a delay time corresponding to the flow rate measured from the relation between a flow rate which is set in advance, and the measured delay time. After the passage of this delay time the ultrasonic wave is emitted from the generator on the basis of a driving signal outputted from a trigger section and the flow rate is determined. Since the flow rate is thus measured with the delay time suitable for the flow rate, the flow rate is correctly determined, and power consumption is reduced.
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