Apparatus for detecting changes in parameters of liquid flowing in a pipe based on sing-around method

Claim 1

An apparatus for detecting a change in parameters of a liquid flowing in a pipe based on the sing-around method, which comprises: a set of a transmitting probe and a receiving probe arranged opposite to each other on the outer surface of a pipe, said transmitting probe emitting an ultrasonic pulse through a liquid flowing in said pipe to said receiving probe, and said receiving probe converting said ultrasonic pulse from said transmitting probe into a voltage signal and transmitting said voltage signal; an amplifier for amplifying said voltage signal from said receiving probe; a masking circuit for transmitting a masking signal in response to said signal from said receiving probe as amplified by said amplifier, said masking circuit masking, during a preset masking time, noise signals other than normal ones from among signals from said receiving probe; a one-shot pulse generator circuit for transmitting a pulse in response to said making signal from said masking circuit; a masking time setup circuit for setting up said masking time, said masking time setup circuit beginning actuation immediately upon resetting of a timer thereof in response to said pulse from said one-shot pulse generator circuit, and releasing said masking by said masking circuit by transmitting a masking release signal to said masking circuit at the moment when said masking time has elapsed, and said masking time being set up at a desired value by said timer within a range of periods slightly smaller than the sing-around period corresponding to a liquid flowing in said pipe giving the highest sound velocity and sufficient to permit masking of said noise signals; a receiving monitor-time setup circuit for setting up a receiving monitor time during which interruptions of pulses transmitted from said one-shot pulse generator circuit are monitored, said receiving monitor-time setup circuit beginning actuation immediately upon resetting of a timer thereof in response to said pulse from said one-shot pulse generator circuit, and transmitting a signal when said timer has not been reset again by the next pulse from said one-shot pulse generator circuit during said receiving monitor time, and said receiving monitor time being setup by said timer at a desired value slightly larger than the sing-around period corresponding to a liquid flowing in said pipe giving the lowest sound velocity; a pseudo-pulse generator circuit for transmitting a pseudo-pulse to said masking circuit in response to said signal from said receiving monitor-time setup circuit, said pseudo-pulse, like said signal from said receiving probe, causing said masking circuit to transmit a masking signal in response to said pseudo-pulse; a voltage/power converter circuit for converting said pulse from said one-shot pulse generator circuit into a power signal and transmitting said power signal to said transmitting probe, said transmitting probe transmitting the next ultrasonic pulse in response to said power signal, and thus the sing-around actuation being continued; and an output section for taking out a pulse from said one-shot pulse generator circuit as an output, said output section comprising a frequency/voltage converter circuit and a recorder.

Claim 2

An apparatus for detecting a change in parameters of a liquid flowing in a pipe based on the sing-around method, which comprises: a set of a transmitting probe and a receiving probe arranged opposite to each other on the outer surface of a pipe, said transmitting probe emitting an ultrasonic pulse through a liquid flowing in said pipe to said receiving probe, and said receiving probe converting said ultrasonic pulse from said transmitting probe into a voltage signal and transmitting said voltage signal; an amplifier for amplifying said voltage signal from said receiving probe; a masking circuit for transmitting a masking signal in response to said signal from said receiving probe as amplified by said amplifier, said masking circuit masking, during a preset masking time, noise signals other than normal ones from among signals from said receiving probe; a one-shot pulse generator circuit for transmitting a pulse in response to said making signal from said masking circuit; a masking time setup circuit for setting up said masking time, said masking time setup circuit beginning actuation immediately upon resetting of a timer thereof in response to said pulse from said one-shot pulse generator circuit, and releasing said masking by said masking circuit by transmitting a masking release signal to said masking circuit at the moment when said masking time has elapsed, and said masking time being set up at a desired value by said timer within a range of periods slightly smaller than the sing-around period corresponding to a liquid flowing in said pipe giving the highest sound velocity and sufficient to permit masking of said noise signals; a receiving monitor-time setup circuit for setting up a receiving monitor time during which interruptions of pulses transmitted from said one-shot pulse generator circuit are monitored, said receiving monitor-time setup circuit beginning actuation immediately upon resetting of a timer thereof in response to said pulse from said one-shot pulse generator circuit, and transmitting a signal when said timer has not been reset again by the next pulse from said one-shot pulse generator circuit during said receiving monitor time, and said receiving monitor time being setup by said timer at a desired value slightly larger than the sing-around period corresponding to a liquid flowing in said pipe giving the lowest sound velocity; a pseudo-pulse generator circuit for transmitting a pseudo-pulse to said masking circuit in response to said signal from said receiving monitor-time setup circuit, said pseudo-pulse, like said signal from said receiving probe, causing said masking circuit to transmit a masking signal in response to said pseudo-pulse; a voltage/power converter circuit for converting said pulse from said one-shot pulse generator circuit into a power signal and transmitting said power signal to said transmitting probe, said transmitting probe transmitting the next ultrasonic pulse in response to said power signal, and thus the sing-around actuation being continued; and an output section for taking out a pulse from said one-shot pulse generator circuit as an output, said output section comprising a frequency/voltage converter circuit and a recorder.