PURPOSE: To eliminate the measurement errors maintaining the directivety of ultrasonic waves by receiving the signal outputted from an ultrasonic wave oscillator with oscillator with a receiver while the temperature of the fluid is detected to change the oscillation frequency.
CONSTITUTION: An ultrasonic wave transmitter 2 is mounted on the outer wall of the piping 1 and ultrasonic wave receivers 3 and 4 are mounted at a symmetrical position on the opposite side. The output signal of the receivers 3 and 4 is amplified with amplifiers 5 and 6 and as the fluid 11 to be measured flows in the direction of the arrow, in the pattern of intensity, the output voltage shifts in the direction of the arrow as a whole. Consequently, since the output voltage of the receiver 4 is larger than that of the receiver 3, the difference in the output voltage is indicated with a differential amplifier 7 and the value is converted into the flow rate and indicated with a meter 8. The output from the transmitter 2 is projected to a fluid 11 with the output of an oscillator 10 passing through a power amplifier 9. The temperature of the fluid 11 is directly detected with a thermocouple 12 provided and inputted into a temperature frequency correction circuit 13 to control the voltage so that the oscillation frequency of the oscillator 10 rises in proportion to the temperature. By this, the directivity of the ultrasonic beam is maintained constant.
UESUGI NOBUO
WADA ICHIROU
HAYASHIDANI SADAYOSHI
