JPS5937420A - Correlation flowmeter - Google Patents

Abstract

PURPOSE:To make operation sure and to improve accuracy and reliability by constituting a detector for obtaining the 1st and the 2nd phase noise signals of a voltage control phase shifter, a phase comparator and a low pass filter. CONSTITUTION:A phase comparator 82 detects the phase difference between the wave received in the 1st ultrasonic wave receiving element 6 and the driving voltage of the 1st ultrasonic wave oscillating element 3 which is adequately shifted in phase and separates the random fluctuating component in the phase of the received wave in accordance with said difference in, for example, the 1st detector 8. A phase shifter 81 for controlling voltage and a low pass filter 83 controls the phase shift angle of the shifter 81 so that the output average value of the comparator 82 always attains the specified value near the center in the operation range of the phase comparator. The outputs of the 1st and the 2nd detectors 8, 9 are inputted to a correlator 10. The mutual correlation between the 1st signal and the 2nd signal delayed by a time (t) is determined in the correlator 10, and the value (t) that maximizes the correlation coefft. thereof is calculated. The flow rate is displayed on a flow rate calculating display device 11.

Description

[Detailed description of the invention] The present invention relates to a correlated flow needle.

Ultrasonic oscillation elements are provided at a certain distance on the upstream and downstream sides of the pipe through which the fluid whose flow rate is to be measured, and ultrasonic beams are emitted parallel to each other approximately in the diametrical direction of the pipe. The two (2) ultrasonic receiving elements provided opposite to the above two ultrasonic oscillating elements, respectively, receive the ultrasonic waves that have passed through the fluid in the flow path, and the ultrasonic waves contained in each received wave are Extract random fluctuation components of amplitude, phase or frequency,
A signal obtained by giving an appropriate delay time t to a random fluctuation signal (hereinafter referred to as the first signal) obtained from the upstream receiving element (hereinafter referred to as the first signal delayed by the time t); The value of the delay time t that maximizes the correlation coefficient with the random fluctuation signal obtained from the downstream receiving element (hereinafter referred to as the second signal) is determined, and during this time t the fluid is exposed to both of the above ultrasonic beams. Correlated flow needles are known that determine the flow rate or flow rate of a fluid as the time it takes to pass between the two.

Furthermore, as microcomputers with higher speeds and larger capacities are now available at lower prices, consideration is being given to using not only ultrasonic waves but also optical signals, especially laser beams, as probe waves.

In addition, in this correlation flow rate needle, instead of the true correlation coefficient calculated directly from the second signal and the first signal delayed by time t, the average value (3) of those signals is calculated. It is also known to utilize a polarity correlation coefficient calculated for a so-called polarity signal indicating magnitude.

However, conventionally known correlated flow rate needles do not have sufficient accuracy, do not necessarily operate stably, and often malfunction.
There was a problem of lack of reliability.

The reason for this is that the random fluctuation components in the probe waves that have passed through the fluid, that is, the first and second signals themselves cannot be correctly grasped.

In other words, these second and second signals can be perceived as noise superimposed on the fundamental wave in the transmitted wave, but the amplitude, phase, etc. of the fundamental wave can vary considerably depending on the temperature, pressure, composition, etc. of the fluid. It is particularly difficult to separate this fluctuation from the noise caused by the fluid flow.

The present invention has been made based on the above-mentioned viewpoints, and an object thereof is to provide a correlated flow needle that operates reliably and has high precision and reliability.

Therefore, the gist of the present invention is to employ random phase fluctuation signals as the first and second signals, and to use a detector for obtaining this phase noise signal.
It is composed of a voltage-controlled phase shifter, a phase comparator, and a low-pass filter, and thereby always correctly separates phase fluctuations unrelated to the flow rate of the fundamental wave from significant phase noise caused by flow disturbance. The aim is to measure the flow velocity or flow rate based on the obtained phase noise signal.

Hereinafter, details of the configuration of the present invention will be explained with reference to the drawings.

The drawing is an explanatory view showing one embodiment of the correlated flow rate needle according to the present invention, and in the figure, 1 is inserted and connected to a pipe line 2.2 through which a fluid whose flow rate is to be measured flows, forming a part of the flow passage. casing of the flow rate detection unit; 3 is a first ultrasonic oscillation element that is attached to the casing 1 and can emit ultrasonic waves into the fluid flowing within the casing 1; 4 is downstream from the first ultrasonic oscillation element 3; A second ultrasonic oscillation element 5 is attached to the housing 1 on the side and is capable of emitting ultrasonic waves substantially parallel to the first ultrasonic oscillation element 3. Activating pulse (5) Oscillators 6 and 7 are first and second ultrasonic receiving elements that receive the ultrasonic waves oscillated by the first and second ultrasonic oscillating elements 3.4 and transmitted through the fluid, respectively; 8 and 9 are first and second detectors that detect random phase fluctuation components contained in the outputs of the first and second ultrasonic receiving elements 6 and 7, respectively; 10 is a first detector 8; A correlator 11 calculates the value of the delay time t at which the correlation coefficient becomes the maximum value by cross-correlating the function obtained by giving a delay time t to the output of the second detector 9 and the output function of the second detector 9. This is a calculation display for flow velocity or flow rate.

In other words, the gist of the present invention is to replace the first and second detectors 8.9 with first and second voltage-controlled phase shifters 81 and 91, and second and second phase comparators, respectively. vessels 82 and 9
2. It is constituted by the first and second low-pass filters 83 and 93.

All conventionally known detectors consisted only of phase comparators. Therefore, for example, if the temperature, pressure, or composition of the fluid changes and the phase of the fundamental wave in the transmitted wave changes,
The operating point had moved (6), and malfunctions were unavoidable.

In the present invention, due to the effects of the first and second voltage controlled phase shifters 81 and 91 and the second and second low pass filters 83 and 93, the first and second voltage controlled phase shifters 82
Since the operating points of and 92 are always kept constant, no problem occurs even if the phase of the fundamental wave changes.

Since the configurations of these first and second detectors 8.9 are the same, only the first detector 8 will be described here.

In the present invention, the random fluctuation component of the phase of the received signal of the first ultrasonic receiving element 6 is captured as a fluctuation in the phase difference between the received signal and the drive voltage of the first ultrasonic oscillating element 3.

That is, the phase comparator 82 detects the phase difference between the received wave of the first ultrasonic receiving element 6 and the driving voltage of the first ultrasonic oscillating element 3, which is appropriately phase-shifted. Separate the random fluctuation components of the phase.

(7) In addition, the voltage-controlled phase shifter 81 and the low-pass filter 83 are configured such that the average output value of the phase comparator 82 is always a constant value, a value near the center of the operating range of the phase comparator.
This controls the phase shift angle of 1.

The outputs of these first detector 8 and second detector 9 are input to a correlator 10.

The correlator 10 is a well-known device, so a detailed explanation will be omitted, but the correlator 10 cross-correlates the first signal and the second signal delayed by the time t, and calculates the correlation between the first and second signals. The value of t that maximizes the relational coefficient is calculated, and the flow rate is displayed on the flow rate calculation display 11.

Since the present invention is configured as described above, when the present invention is used, the random fluctuation component of the phase of the fluid-transmitted wave can be accurately grasped at all times, so the 'fIl amount or flow velocity is always measured correctly, and therefore the action is This provides a stable, accurate, reliable and useful correlated flow needle.

The configuration of the present invention is not limited to the above-mentioned embodiments, and not only ultrasonic waves but also laser light and other short wavelength electromagnetic waves can be used as exploration waves, and each (8) circuit component can also be used. Known devices having the same or equivalent functions as those described above can be widely used, and in particular, the configurations of the first detector 8 and the second detector 9 can be freely changed in stages within the scope of the purpose of the present invention. For example, instead of a low-pass filter, an integrating circuit, a smoothing circuit, a band-pass filter, etc. can be used, and the present invention encompasses all of them.

[Brief explanation of drawings]

The drawing is an explanatory view showing one embodiment of the correlated flow rate needle according to the present invention. 1--・・-・-------・-Housing 2----------・----1 Pipeline 3----------・--1--1st Ultrasonic oscillation element 4-------・-----・Second ultrasonic oscillation element 5-----1.-Pulse oscillator 6----
−−−−−・−−−First ultrasonic receiving element? ---
------------- - - - - - - - - - - - - Second ultrasonic receiving element 8 - -
-----------First detector 9-----
---Coco--Second detector (9) 10-----・-------Correlator 11--
-----------Full flow rate calculation display 81.91-・
--- and second voltage-controlled phase shifter 82.92 ---
-------First and second phase comparators 83.93--
----1.I- and second low-pass filter patent applicant Oval Equipment Industry Co., Ltd. Agent (7524) Shotabe Mogami (10)

Claims (1)

[Claims] A casing of a flow rate detection unit inserted into a pipe, a first oscillation element attached to the casing and capable of emitting a probe wave into the casing, and a first oscillation element facing the first oscillation element. a first receiving element that is attached to the housing and can receive the probe wave oscillated from the first oscillation element; and a first oscillation element that is attached to the housing on the downstream side of the first oscillation element. a second oscillation element capable of emitting exploration waves into the housing in parallel; and a second oscillation element mounted on the housing facing the second oscillation element and capable of receiving exploration waves oscillated from the second oscillation element. a receiving element, an oscillator for operating the first and second oscillating elements, and first and second detection for detecting random phase fluctuation components in the received waves received by the first and second receiving elements, respectively. The interaction (1 ) In the correlation flow needle, which is composed of a correlator that takes correlation and calculates the value of t at which the correlation coefficient becomes maximum, and a device layer that calculates the flow velocity or flow rate in response to the output of the correlator, - and a second detector receive and phase-shift the voltage waves that actuate the first and second oscillation elements, respectively.
and a second voltage-controlled phase shifter, and a phase comparator that compares the first and second signals with the outputs of the second and second voltage-controlled phase shifters, respectively; The above-mentioned correlated flow rate needle is characterized in that it is constituted by a low-pass filter inserted between the output terminal of the comparator and the control input terminals of the first and second voltage-controlled phase shifters.