JPS5589717A - Ultrasonic wave flow meter - Google Patents

Abstract

PURPOSE:To increase the measuring accuracy of flow, by detecting the phase difference by zero cross point without level variation, as to the two reception signals in which the reception signal level reaches more than a certain level. CONSTITUTION:The signal transmitted from the transmitters 31, 32 of the measuring section 3 transmits measured liquid 33, the forward reception signal is received at the receiver 35 and reverse reception signal is at the receiver 36, and adjustment is made at the phase adjustment circuits 5a, 5b so that the phase difference of reception signals can be zero when flow is zero. The output of the circuit 5a of forward reception signal is compared at the comparison circuit 6 and rectangular wave F is obtained when it is more than preset level. Further, the output of the circuits 5a, 5b is fed to the wave shape circuits 7a, 7b, to form the rectangular waves G, H, which rise or fall at zero cross points. The rectangular waves F, G, H thus obtained are fed to the phase comparison circuit 8. The phase difference of reception signal in forward and reverse direction, wave shaped on and after the output of the signal from the comparison circuit 6 is detected to measure the flow.