| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic gas meter for measuring a flow rate for a short period, discriminating an appliance, monitoring the safety, and implementing an accurate measurement in a low current consumption. SOLUTION: The ultrasonic gas meter comprises: a transmitting means 2 for transmitting an ultrasonic signal; a receiving means 3 for receiving the ultrasonic signal; a direction switching means 3 for switching the transmitting means and the receiving means, and changing the transmitting/receiving direction of the ultrasonic signal; a measurement control means 1 for measuring a propagation time in the direction indicated by the direction switching means until the ultrasonic signal transmitted from the transmitting means is received by the receiving means, and implementing a propagation time measurement for a period T2 as 1/N of a normal period T1; a calculating means 1 for obtaining the flow rate from the propagation time measured for the period T2; a safety logic operating means 6 for determining whether the gas flow rate is abnormal or not from the flow rate obtained by the calculating means 1; a calculating means 2 for obtaining the flow rate from the propagation time measured for the period T1; an accumulating means 8 for accumulating a result from the calculating means 2; and a minute leakage sensing means 9 for detecting a minute leakage. COPYRIGHT: (C)2010,JPO&INPIT
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