| 摘要 |
PROBLEM TO BE SOLVED: To keep the amplitude of a received signal at a specified value, when adjusting the driving voltage of an ultrasonic transmitter corresponding to the change of the propagation efficiency of an ultrasonic wave propagating in a fluid to be measured. SOLUTION: This ultrasonic type vortex flowmeter 10 detects Karman vortex generated in proportion to the flow rate in the downstream of a vortex generator 16 by utilizing phase modulation of the ultrasonic wave, and acquires the flow rate of the fluid to be measured. A control circuit 58 has a flow rate operation part 60 for operating the flow rate of the fluid to be measured from the phase modulation of the ultrasonic wave, an amplitude adjusting part 62 for controlling the driving voltage so that the amplitude of the received signal outputted from reception side ultrasonic sensors 34, 36 agrees with a value set beforehand or enters a set range, and an abnormality detection part 63 for detecting and reporting abnormality generation when the amplitude of the received signal is not controlled below the specified value after finish of the amplitude adjustment. Therefore, even when the propagation efficiency of the ultrasonic wave is high, the measurement accuracy can be kept by controlling the voltage of a driving signal below a prescribed value, and by securing a sufficient received voltage under normal pressure.
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