| 摘要 |
PROBLEM TO BE SOLVED: To provide a flow measuring device for fluid capable of automatically setting a reference voltage without manpower and automatically readjusting it even in case of a secular change after setting. SOLUTION: In this flow measuring device for fluid, the reference voltage is changed from a minimum to a maximum by a reference setting means 14, peak voltages of received waves are recognized from a plurality of inflexion points where the time difference clocked by a time difference clock means 13 is largely changed at that time, and the reference voltage is set to a middle voltage or an optional point among specified two or three peak voltages based on the ratio of the peak voltages. According to this, the reference voltage can be set to a voltage capable of detecting the arrival time of an ultrasonic signal most stably to the voltage fluctuation of received signals of ultrasonic received waves. Even after setting the reference voltage, reset of the reference voltage is performed by the reference setting means 14 when the time difference clocked by the time difference clock means 13 in flow measurement is out of a predetermined time difference width determined based on the time difference at the time of setting the reference voltage, whereby the reference voltage can be regularly kept in an optimum state. COPYRIGHT: (C)2005,JPO&NCIPI
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