JPH04318455A - Ultrasonic concentration measuring instrument - Google Patents

Abstract

PURPOSE:To obtain a concentration measuring instrument which can accurately measure the concentration of a fluid, such as silt, etc., or a fluidized body irrespective of the variation of the transmitting output, variation of the converting efficiency, or variation of the receiving amplification degree of the instrument. CONSTITUTION:This ultrasonic concentration measuring instrument is composed of a transducer 1, transducer 2, and a plurality of reflectors A and B which are arranged at different distances in the same direction against the transducer 2. The damping amount per unit distance of reflected waves by silt, etc., is found from the ratio between the received wave amplifying signal of the reflected waves from the reflector A and that of the reflected waves from the reflector B and the concentration of the silt, etc., corresponding to the damping amount is found.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the concentration of sludge or the like by measuring the propagation attenuation of ultrasonic waves.

0002

2. Description of the Related Art The higher the concentration of ultrasonic waves propagating in sludge, etc., the greater the attenuation during propagation. That is, the amount of attenuation is a function of concentration. Therefore, if the correlation between the concentration and the attenuation amount is investigated in advance, the concentration can be determined by measuring the attenuation amount.

Conventionally, as shown in FIG. 3, a system for measuring concentration as described above includes an ultrasonic wave transmitter 6 and a wave receiver 7 placed opposite each other in the sludge or the like 3 to be measured. The transmitter 6 applies an electric signal of ultrasonic frequency from the transmitter 4 to transmit the ultrasonic wave into the sludge etc. 3, and the receiver 7 receives the ultrasonic wave propagated through the sludge. wave, converts it into an ultrasonic electrical signal, and sends it to the receiver 5.

The receiver 5 amplifies the level of the input signal to a required level, compares it with a preset reference level, converts it to density, and outputs it as a density instruction signal.

[0005]

However, in the conventional system described above, over a long period of time, the transmitter 4
The transmission output of the transmitter 6 or receiver 7 may change, or the sensitivity (
If the conversion efficiency (conversion efficiency) changes or the amplification degree of the receiver 5 changes, the signal level will change before it is converted into a concentration indication signal, and even if the concentration of sludge etc. 3 does not change, the concentration will change. There has been a problem in that a concentration indicating signal that appears as if the image has been removed is output, making it impossible to accurately measure the concentration.

In view of the problems of the prior art described above, an object of the present invention is to eliminate the effects of fluctuations in the output of the transmitter, the sensitivity of the transmitter and receiver, and the amplification degree of the receiver. An object of the present invention is to provide a concentration measuring device capable of measuring concentration without being exposed to water.

[0007]

[Means for Solving the Problems] The present invention has the following means for achieving the above object. That is, the ultrasonic concentration measurement device of the present invention includes: a transmitter that outputs a pulsed ultrasonic frequency signal; a receiver that can calculate the intensity ratio between signals input with a time difference; and an ultrasonic wave output from the transmitter. A transducer that converts a frequency signal into an ultrasonic wave and transmits the same, and converts the received ultrasonic wave into an ultrasonic frequency electrical signal and sends it to a receiver; Sound waves propagate in the same direction with respect to the transducer. An ultrasonic concentration measuring device characterized by comprising: a plurality of reflectors installed at positions at different distances;

[0008]

[Operation] The operation of the concentration measuring device of the present invention will be explained below. Now, to simplify the explanation, a case will be explained in which there are two reflectors at different distances in the same direction with respect to the transducer.

The reflector closer to the transducer is A, the reflector farther away is B, and the distance from the transducer is lA.
, lB , and the reflection cross sections are σA , σB , respectively.
The reflection coefficients are ηA and ηB, the acoustic power transmitted from the transducer is Pt, the conversion efficiency of the transducer is η, and the amount of attenuation (attenuation coefficient) when propagating by a unit distance l0 is α
(<1), where the amplification degree of the receiver is G, the output after receiving amplification of the signal reflected from reflector A is EA, and similarly the output after receiving amplification of the signal due to reflection from reflector B is EB. When a pulsed ultrasonic frequency signal is output from the transmitter, an output EA expressed by the following equation 1 is obtained after the time required to propagate a distance of 2lA has elapsed. However, K is a proportionality constant.

0010

[Math 1]

Further, after this, 2 of the difference between the distances lB and lA
When the time required to propagate twice the distance has elapsed, an output EB expressed by the following equation 2 is obtained.

0012

[Math 2]

Since the receiver of the present invention calculates the ratio between the input signals with a time difference in this way, Equation 1 and Equation 2
Taking the ratio R of , it becomes as shown in Equation 3.

[0014]

[Math 3]

[0015] Looking at Equation 3, we find that K, Pt, η2
, G have all disappeared, and it can be seen that even if these values change, the value of the ratio R is not affected. Also, the remaining σA
, σB , ηA , and ηB are fixedly determined by the physical structure of the reflector, so once the reflector to be used is decided, they are fixed and will not change over time or change over time unless the reflector is changed. It is of a nature that does not occur.

Further, l0 is a fixed value in unit distance, and lA and lB also become fixed values that do not change if the transducer and the reflectors A and B are fixedly installed. In the end, formula 3
The ratio R is expressed as a function that changes only with changes in the attenuation amount α per unit distance.

By the way, as described in the prior art, since the attenuation amount α is a function of the concentration of sludge, etc., the ratio R can be determined by understanding the relationship between the attenuation amount and the concentration in advance through experiments or the like. This makes it possible to know the concentration.

[0018]

Embodiments Hereinafter, embodiments of the apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of an embodiment. Reference numeral 1 denotes a transmitter/receiver, which has a configuration that combines a transmitter and a receiver referred to in the means configuration. The transducer 2 converts the ultrasonic frequency signal from the transceiver 1 into ultrasonic waves and transmits the waves to the reflectors A and B, and also transmits the ultrasonic waves reflected from the reflectors A and B. The sound waves are converted into electrical signals and sent to the transceiver 1.

FIG. 2 shows this relationship. Figure 2
The waveform at the left end of (a) is the transmitted wave, and after this signal is transmitted, the reflected wave from reflector A is received after a time determined by the propagation speed of the ultrasonic wave and the distance lA has elapsed. . Similarly, after a period of time determined by the propagation speed of the ultrasonic wave and the distance IB has elapsed, the reflected wave from the reflector B is received.

FIG. 2(b) shows the waveform after amplification and detection of the received ultrasonic electrical signal by the transmitter/receiver 1. The signal reflected from reflector A appears as EA, and the signal reflected from reflector B appears as EB. The transmitter/receiver 1 calculates the ratio between EA and EB, calculates the attenuation amount α per unit distance of sludge, etc. from Equation 3, extracts the corresponding concentration from this attenuation amount α, and generates a concentration indication signal. Output as .

[0021]

As explained above, the concentration measuring device of the present invention receives and amplifies ultrasonic waves reflected from a plurality of reflectors at different distances in the same direction with respect to the transducer. By calculating the ratio of the detected outputs, the amount of attenuation per unit distance of sludge, etc. is determined, and the concentration corresponding to this amount of attenuation is indicated, so the transmission output, the conversion efficiency of the transducer, and the reception amplification This method has the advantage of being able to accurately measure concentration without being affected by changes over time or changes over time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transmitted wave, a received wave, and a waveform after being amplified and detected by a transceiver in the device of the present invention.

FIG. 3 is a block diagram showing the configuration of a conventional concentration measuring device using ultrasonic waves.

[Explanation of symbols]

1 Transmitter/receiver 2 Transducer/receiver 3. Sludge, etc. 4 Transmitter 5 Receiver 6 Transmitter 7 Receiver A Reflector B Reflector

Claims (1)

[Claims] Claim 1: A transmitter that outputs a pulsed ultrasonic frequency signal; A receiver that can calculate the intensity ratio between input signals with a time difference; Converts the ultrasonic frequency signal from the transmitter into an ultrasonic wave. a transducer/receiver that converts the received ultrasonic wave into an ultrasonic frequency electrical signal and sends it to a receiver; An ultrasonic concentration measuring device comprising: a plurality of reflectors; and a plurality of reflectors.