KR100439656B1 - Non-contact type temperature distribution instrumentation system by using ultrasonics - Google Patents

Abstract

The present invention relates to a non-contact temperature distribution measuring apparatus capable of measuring in real time the surface and internal temperature distribution of the previously unmeasurable properties using nonlinear effects of ultrasonic waves. More specifically, high-power impulse waves are transmitted into the medium to induce nonlinear coupling between the medium and the transmission wave, thereby reading the nonlinearity of the sound waves through a separate phase modulation state of the continuous ultrasound and demodulating the phase distribution of the continuous ultrasound. Temperature distribution) can be measured in real time.

According to the present invention, there is provided an ultrasonic vibration means for performing a wave and a wave of a pump wave which causes a nonlinear effect in a medium; Generator means for performing electrical and acoustic signal conversion from said ultrasonic vibration means; Signal processing means for performing arithmetic processing on the signal detected from said generating device means; Overcurrent protection means for preventing a specific current abnormality from flowing for the safety of the measuring apparatus and the user; Connection logic means for sequentially processing a large amount of high-speed data input and output from the signal processing means; Control means for providing an interface with the outside, performing information processing for real-time measurement, and performing control and measurement of all components; Remote control means for performing measurements by serial communication from the outside through a PC that is remotely connected to the signals controlled and measured by the control means; A non-contact temperature distribution measuring apparatus including a key input / display means for displaying a control state or a measured value by the control means and performing key input of a measuring apparatus is provided.

Description

Non-contact type temperature distribution instrumentation system by using ultrasonics}

The present invention relates to a non-contact temperature distribution measuring apparatus capable of measuring in real time the surface and internal temperature distribution of the previously unmeasurable properties using nonlinear effects of ultrasonic waves.

More specifically, high-power impulse waves are transmitted into the medium to induce nonlinear coupling between the medium and the transmission wave, thereby reading the nonlinearity of the sound waves through a separate phase modulation state of the continuous ultrasound, and demodulating the phase distribution of the continuous ultrasound. The present invention relates to a device capable of measuring temperature distribution in real time.

In general, the measurement method using the wave (sound wave) has been the (linear) measuring system so far to measure the temperature (velocity) by observing the temperature (velocity) dependence of the wave as the propagation time. In this case, what is actually obtained is the average temperature (speed) in the direction in which the sound waves have passed.

On the other hand, impulse pump waves are transmitted to the ultrasonic wave in the medium, and the phase and temperature dependence (nonlinear effects) of the phase generated by interaction with the physical properties of the medium are modulated separately. It is possible to measure the phase distribution (ie temperature or velocity distribution) of sound waves at once by reading them with ultrasonic waves and performing modulation and demodulation signal processing. This is, in principle, to measure the distribution of physical quantities in space, so there is a big advantage that real-time measurement is possible regardless of the surrounding environment of the measurement part such as the outer wall located on the measurement line.

The measuring device using such a nonlinear effect uses two ultrasonic waves called a pump wave and a probe wave. Pump waves require high sound pressure impulse waves to cause nonlinear effects. The probe wave is a continuous wave of high amplitude and small amplitude to observe the nonlinear effect induced by the pump wave. When these two waves overlap each other, the sound velocity of the probe wave receives not only the sound velocity change due to the sound pressure change of the paja but also the sound speed change due to the sound pressure change of the pump wave. Fluctuations in the speed of sound are obtained by phase modulation of the probe wave. The phase change of the probe wave due to the nonlinear effect is expressed as a function of the spatial distribution of the physical property to be measured and the sound pressure waveform of the pump wave. As a result, the spatial distribution of the physical properties over the ultrasonic beam is obtained.

That is, high-power impulse wave is transmitted into the medium to induce nonlinear coupling between the medium and the transmission wave, and the nonlinear degree of the sound wave is read through a separate phase shift state of the continuous ultrasonic wave and demodulated. Thus, the phase distribution (expressed as the distribution of temperature or velocity) of continuous ultrasound can be measured in real time.

Using existing infrared rays, the surface temperature distribution can be measured, but the temperature distribution inside the physical properties is unknown. However, the measuring instrument of the present invention using ultrasonic waves can measure not only surface temperature but also previously impossible information such as internal temperature distribution and heat flow distribution.

In addition, various technologies such as medical devices, flaw detectors, flow meters, level meters, thickness meters, and the like have been developed using ultrasonic technology, but a temperature distribution measuring device using nonlinearity of ultrasonic waves has not been developed yet.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to apply a principle of ultrasonic nonlinear effect to develop a high-power ultrasonic transceiver module and pulse amplifier design, and to develop a high precision signal processing circuit and a program. It is to provide a measuring device that can measure the temperature and the temperature distribution of.

As a technical idea for achieving the above object of the present invention

Ultrasonic vibration means for carrying out the wave and the wave of the pump wave causing the nonlinear effect in the medium; Generator means for performing electrical and acoustic signal conversion from said ultrasonic vibration means; Signal processing means for performing arithmetic processing on the signal detected from said generating device means; Overcurrent protection means for preventing a specific current abnormality from flowing for the safety of the measuring apparatus and the user; Connection logic means for sequentially processing a large amount of high-speed data input and output from the signal processing means; Control means for providing an interface with the outside, performing information processing for real-time measurement, and performing control and measurement of all components; Remote control means for performing measurements by serial communication from the outside through a PC that is remotely connected to the signals controlled and measured by the control means; It provides a non-contact temperature distribution measuring device, characterized in that it comprises a key input / display means for displaying the control state or the measured value by the control means and performs a key input of the measuring device.

1 is a block diagram of a non-contact temperature distribution measuring apparatus according to the present invention.

<Description of Symbols for Major Parts of Drawings>

100: pump wave transmitter 102: probe wave transmitter

104: probe wave receiver 106: probe wave generator

108: probe wave drive 110: pump wave generator

112: pump wave drive 114: probe wave detector

116: bandpass filter 118: phase demodulator

120: synchronous adder 122: signal processor

124: overcurrent protection circuit 126: connection logic machine

128: mass memory 130: central processing unit

132: communication controller 134: external communication unit

136: display device 138: key button

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the embodiment of the present invention will be described in detail. First, the nonlinear effect of the ultrasonic waves according to the present invention will be formulated.

Sound pressure in the gas at given entropy S Changes in the density of the medium It is related to the change. In general, assuming a slight change in density, sound pressure develops into the Taylor series.

here Is static pressure, Is the density of the medium at constant pressure. In a conventional linear wave, only the first term of the Taylor series is considered. In the case of non-linear waves, even the secondary term of Taylor series is considered. That is, Equation 1 is given as follows.

Where A and B are magnitudes that determine the nonlinear effect, given by

,

And nonlinear parameters are defined as B / A. In Equation 3 above Represents the speed of sound waves at constant pressure. Considering this nonlinear effect, the sound wave c is the change in sound pressure in Equation 2 Is displayed.

If to be. Pressure change Where is positive, it means that the speed of sound waves increases. In other words, sound waves propagate and are dispersed at the same time. This transformation is related to the phase change of sound waves, and the relation can be expressed as follows.

Then, using Equation 5, it is possible to obtain a change in the phase of the sound wave according to the pressure change.

At this time, Is the phase shift parameter

It is defined. Therefore, it is shown that the change in pressure depending on the position can be detected through the variation of sound waves. Equation 6 is a basic equation representing the speed dependence of sound pressure, and has a specific value inherent to the medium in which the ultrasonic waves are propagated.

In particular, since the structural change is small when the medium is a gas, the nonlinear parameter B / A included in the phase change parameter is constant.

Therefore, in gaseous media, measurement of parameter distributions that contribute to other sound velocity densities and sound pressures is the subject of study. Here, the generation mechanisms of these parameters are numerically established to establish the theoretical basis of the specification design for the measurement system, and the phase change parameters of various media are investigated to estimate the accuracy of the measurement according to the media.

Next, the basic principle of the application of the measurement system using the nonlinear effect is as follows.

Meters using nonlinear effects use pumping waves and probe waves. The pump wave is a high sound pressure impulse wave to exhibit a nonlinear effect, and the probe wave is a continuous wave of high amplitude small amplitude to observe the nonlinear effect caused by the pump wave. These two waves overlap and interference occurs, and the velocity of the probe wave varies with the sound pressure of the wave itself. Speed change and sound pressure change of pump wave This causes a change in speed.

The second term on the right side of Equation 8 is the effect of the sound pressure variation of the probe wave itself, and the third term is the effect of the pump wave. If the sound pressure of the pump wave at the sound pressure of two sound waves is sufficiently large compared with the sound pressure of the probe wave, the spatial distribution of the total sound pressure can be regarded as the sound pressure distribution of the pump wave. The speed of sound waves can be expressed simply as

The physical properties and nonlinearity we measure are related to the phase modulation parameters in Equation 4. As a result, the change in sound velocity is represented by the phase modulation of the probe wave. The interval between the transmitter and the receiver measurement period Assuming that the pump waves are distributed on these beams, the phase modulation of the probe waves can be expressed as follows.

here, Location The wave number of the probe wave at Is each frequency. The phase change of the probe wave due to the nonlinear effect finally detected is expressed as follows.

In other words, the phase change is measured by Pressure distribution of the shunt and pump wave It is expressed in the form of convolution of. Phase change amount We measure the spatial distribution of physical properties In Equation (11), the Fourier transform and the Fourier transform can be obtained.

Based on the above basic concept, the basic principle of the measurement system is established by applying to actual conditions.

Next, a block configuration diagram of the non-contact temperature distribution measuring apparatus shown in FIG. 1 will be described.

The measuring apparatus shown in FIG. 1 includes a pump wave transmitter 100, a probe wave transmitter 102, and a probe wave receiver 104, which transmit and receive a pump wave that causes nonlinearity in a medium. Ultrasonic vibration means for performing waves; Probe wave generator 106, probe wave drive 108, pump wave generator 110, pump wave drive 112, probe wave detector 114, bandpass filter 116, phase demodulator 118, synchronous adder Generating device means for performing electrical / acoustic signal conversion with the ultrasonic vibration means; and a signal processor 122 for performing arithmetic processing on the signal detected from the generating device means. Processing means; An over-current protection means including an over-current protection circuit 124 to prevent a specific current abnormality from flowing for the safety of the measuring apparatus and the user; A connection logic unit having a connection logic machine 126 for sequentially processing a large amount of high-speed data input and output from the signal processing means; A mass memory 128 and a central processing unit 130 to provide an interface with the outside, perform information processing for real-time measurement, and control means for controlling and measuring all components; A remote control means having a communication controller (132) and an external communication unit (134) for performing measurement by serial communication from the outside through a PC that is remotely connected to the signals controlled and measured by the control means; A display device 136 and a key button 138 are provided to display a control state or a measured value by the control means, and to constitute key input / display means for performing key input of the measurement device.

The pumping wave transmitter 100 is an oscillator for generating a high sound pressure impulse pump wave causing a local nonlinear effect in a medium.

Normally applying a high voltage DC voltage of about 500 volts to the coil for only a short time of about 100 uSec to form an electromagnetic field, air vibration is generated through a diaphragm made of thin metal plate, which coincides with the probe wave traveling line to obtain an overlapping signal. .

The probe wave transmitter 102 is a wave for observing the nonlinear effect caused by the pump wave and needs a short wavelength wave in terms of spatial resolution and has good directivity.

Generally, a sine wave of about 215 kHz is used, and the output voltage can be increased according to the distance of the object to be measured, but a voltage of about 50 volts is practically used.

In addition, the ultrasonic wave sensor for a probe wave transmitter uses a commercially available ultrasonic wave sensor that resonates at a specific frequency. When a sine wave is directly applied to both ends of the sensor, the ultrasonic wave wave continuously vibrates.

The probe wave receiver 104 is an oscillator for receiving a nonlinear effect in a medium sent from the probe wave transmitter 102.

Usually, the same one as the ultrasonic vibration sensor used for the probe wave transmitter may be used, and it is connected to the receiving signal processing unit without the bias of the DC voltage. The receiving bandwidth of the sensor is set according to the fundamental frequency component of the pump wave. When the pulse width of 100 uSec is used, the sensor has a 10 kHz frequency band.

The probe wave generator 106 is a circuit part for generating an electrical signal for driving the probe wave transmitter 100 and generates a fundamental wave by a precision crystal oscillator, and provides a phase for free conversion to a desired frequency. A control oscillator; There is a narrow band pass filter that makes a square wave a sine wave.

The probe wave drive 108 is a circuit part that amplifies the probe wave generated by the probe wave generator 106 and applies it to a probe wave transmitter sensor (ultrasound vibrator). Amplify to about 50 volts (V).

The pumping wave generator 110 is a circuit part for generating a reference pulse signal applied to the pump wave drive, and typically generates only one pulse in accordance with a measurement period.

The measurement period, that is, the pulse period of the pump wave is set between 1 Hz and 0.01 Hz. The faster the pulse period, the shorter the measurement time, while the larger the charging current of the pump wave drive 112 should be. This is because a problem occurs that requires a high-voltage power supply having a large current capacity.

The pumping wave drive 112 converts a pulse signal of a TTL level (0 to 5 volts voltage level) generated by the pump wave generator 110 into a high voltage pulse signal of about 500 volts, thereby pumping a wave wave sensor. The circuit portion for driving the.

The basic configuration of this part is a high-voltage DC power supply, which charges a series connection circuit of a coil and a charging capacitor which functions as an inductor for a long time, and then instantaneously adjusts the width of the capacitor according to the pulse width generated by the pump wave generator 110. The charging current is discharged so that a high voltage, high current discharge signal is induced across the coil.

The probe wave detector 114 is a circuit unit for converting the ultrasonic waves received from the probe wave receiver 104 into an electrical signal and performing amplification so as to amplify the minute signal to a sufficient voltage level. Is composed of two stages connected.

In general, the larger the diameter of the measurement target, i.e., the farther the distance between the transmitting and receiving ultrasonic sensors, the smaller the size of the detected signal, the higher the amplification degree in order to secure a sufficient signal-to-noise ratio. Ensure that the overall amplification is around 60 dB (1000 times voltage amplification).

The band pass filter 116 is a circuit for extracting only a probe wave component from a signal output from the probe wave detector 114, and a center frequency thereof is designed according to the frequency of the probe wave.

The passband should only allow about -5 ~ +5 kHz from the center frequency to cover the band of the pump wave. Accordingly, when using a 215 kHz probe wave and a 10 kHz pump wave, a very narrow narrow band pass filter having a Q factor of about 21.5 should be configured.

The phase demodulator 118 is a circuit for demodulating a signal of a phase-modulated probe wave, and has a signal passed through the bandpass filter 116 and a signal obtained by phase shifting the signal by 90 degrees. Is a circuit that extracts.

The synchronous adder 120 samples and stores the phase demodulated signal of the probe wave output from the phase demodulator 118 in synchronization with the wave of the pump wave.

The signal processor 122 is a part that performs functions related to various signal processing, such as re-adjusting the level of the probe wave or the pump wave when the signal level is too low based on the detected signal.

Since the high voltage signal and the high current signal of the pump wave drive 112 flow in the overcurrent protection circuit 124, a current limiting circuit is provided so as not to flow over a specific current for the safety of the device and the safety of the user.

The connection logic unit 126 is a circuit unit which is positioned between the signal processor 122 and the central processing unit 130 to enable instant processing without direct assistance of the central processing unit 130 when a large amount of high-speed data is input and output.

The large-capacity memory 128 generates a large amount of data because the signal generated by the detector has a high sampling frequency and a high conversion resolution in order to increase the accuracy of the measurement space.

Accordingly, a large-capacity memory unit that operates at high speed is required, and the converted data is temporarily stored there first, and then separately processed by the central processing unit 130. Normally, the FIFO (First In First Out) memory, which is a unidirectional memory dedicated to reading by the central processing unit 130, is dedicated to writing in one direction by the connection logic machine 126.

The central processing unit 130 is responsible for the control and measurement of the entire component, and is a core functional unit that manages the interface with the outside. Typically, a 32-bit high-performance microprocessor or a dedicated digital signal processor is used.

The communication controller 132 is a part that controls the communication standard for exchanging information between each other by connecting a signal controlled and measured by the central processing unit 130 to a computer or other control device that is remotely connected. . Typically, the asynchronous serial access interface (UART) standard is used.

The external communication unit 134 includes a voltage conversion and a connection connector that physically expresses the interface specification of the communication controller 132. RS232 and RS485 drives composed of 9-pin connectors are generally included in the asynchronous serial connection interface (UART) standard. Is used.

The display device 136 is a part for visually displaying a control state or a measured value and typically uses a graphic liquid crystal display (Graphic LCD).

The key button 138 is for recognizing the central processing unit 130 to perform overall control of the device. In general, a plurality of key buttons are combined with the display device 136 to perform overall control.

As described above, according to the non-contact temperature distribution measuring apparatus according to the present invention, it is possible to measure the surface and internal temperature distribution of the previously unmeasurable physical properties by using the nonlinear effect of ultrasonic waves in real time.

First, the internal temperature of the cast can be measured to diagnose the solidification process and provide real-time information to improve the quality of steel and to control the optimal process.

Second, it reduces waste of disposable temperature sensors, improves inaccurate measurement methods for indirect and sample measurements, and enables accurate measurements to the point where measurement has been difficult.

Third, the temperature distribution of the flame or welding machine can be measured to the inside in a non-contact manner can be applied to industrial applications.

Claims (10)

Ultrasonic vibration means for carrying out the wave and the wave of the pump wave causing the nonlinear effect in the medium; Generator means for performing electrical and acoustic signal conversion from said ultrasonic vibration means; Signal processing means for performing arithmetic processing on the signal detected from said generating device means; Overcurrent protection means for preventing a specific current abnormality from flowing for the safety of the measuring apparatus and the user; Connection logic means for sequentially processing a large amount of high-speed data input and output from the signal processing means; Control means for providing an interface with the outside, performing information processing for real-time measurement, and performing control and measurement of all components; Remote control means for performing measurements by serial communication from the outside through a PC that is remotely connected to the signals controlled and measured by the control means; And a key input / display means for displaying the control state or the measured value by the control means and performing key input of the measuring device. The method according to claim 1, wherein the ultrasonic vibration means A pump wave transmitter for generating a high sound pressure impulse pump wave causing a local nonlinear effect in the medium; A probe wave transmitter for observing the nonlinear effect caused by the pump wave; Non-contact temperature distribution measuring apparatus further comprises a probe wave receiver for receiving a non-linear effect in the medium from the probe wave transmitter. The non-contact temperature distribution measuring apparatus of claim 2, wherein an ultrasonic sensor is used as the probe wave transmitter and continuously vibrates by applying a sine wave directly to both ends of the ultrasonic sensor resonating at a specific frequency. The method according to claim 1 or 2, wherein the generator means A probe wave generator for generating an electrical signal for driving the probe wave transmitter; A probe wave driver for amplifying the probe wave generated by the probe wave generator and applying the probe wave to a probe wave transmitter; A pump wave generator for generating a reference pulse signal for driving the pump wave; A pump wave drive for converting a TTL level pulse signal generated by the pump wave generator into a high voltage pulse signal to drive a pump wave transmitter; A probe wave detector for amplifying the ultrasonic wave received by the probe wave receiver into an electric signal; A bandpass filter for extracting only a probe wave component from a signal output from the probe wave detector; A phase demodulator for demodulating a signal of a probe wave subjected to phase modulation; And a synchronous adder for sampling and storing the phase demodulated signal of the probe wave output from the phase demodulator in synchronism with the transmission of the pump wave. The method of claim 4, wherein the probe wave receiver A phase controlled oscillator for generating a fundamental wave by a crystal oscillator and for free converting to a desired frequency; Non-contact temperature distribution measuring device further comprises a narrow band pass filter for making a square wave sine wave. The non-contact temperature distribution measuring apparatus according to claim 4, wherein the pump wave pulse period of the pump wave generator is set between 1 Hz and 0.01 Hz. The method of claim 4, wherein the pump wave drive Charge the series connection circuit of the coil and the charging capacitor as a inductor with a high voltage DC power supply for a long time, and then discharge the charging current of the capacitor instantaneously according to the pulse width generated by the pump wave generator to discharge the high voltage and high current. Non-contact temperature distribution measuring device characterized in that the signal is configured to be guided across the coil. The non-contact temperature distribution measuring apparatus according to claim 4, wherein the probe wave detector is configured by connecting a low noise high gain amplifier in two stages to amplify a minute signal to a sufficient voltage level. The non-contact temperature distribution measuring apparatus of claim 4, wherein the passband of the bandpass filter allows only about -5 to +5 kHz about a center frequency so as to include a band of a pump wave. The non-contact temperature distribution measuring apparatus according to claim 4, wherein the phase demodulator extracts a phase difference between the two signals with a signal passing through a bandpass filter and a signal converted by 90 degrees.