Patent ID: 6435038
Filing Date: 2002-08-20
Classification: G01F,G01P

Abstract:
In an ultrasonic flow velocity measuring apparatus which installs a pair of transducers one of the pair being at an upper stream and the other of the pair being at a lower stream of a fluid passage and measures a flow velocity according to an ultrasonic transit time difference between the ultrasonic transducers, an ultrasonic flow velocity measuring apparatus comprising:a transmitting part for generating an ultrasonic signal having a modulated frequency according to a PN code of a diffusion band; a transducer switching part for alternately applying the ultrasonic signal from the transmitting part to a pair of ultrasonic transducers, and switching a connection state of the pair of ultrasonic transducers for a transmitting or receiving operation; a receiving part for demodulating an output signal of the transducer switching part and capturing a moment at which its own signal is identical with a signal of the transmitting part; a signal synchronization part for locking a synchronization of a receiving signal when the receiving part capture a signal; a time interval measuring part for measuring an ultrasonic transit time under the condition that a synchronization of a receiving signal is locked in the signal synchronization part; and a controller for controlling a switching operation of the transducer switching part, and calculating a flow velocity according to an ultrasonic transit time in opposition to a flow velocity measured by the time interval measuring part.