JP6468790B2 - Ultrasonic leak detection device and leak detection method using the same - Google Patents

Description

  The present invention relates to an ultrasonic leak detection apparatus and a leak detection method using the same, and in particular, an ultrasonic sensor is installed in an environment where a medium such as a liquid exists, and a reflected signal from an object in the liquid is used. The present invention relates to an ultrasonic leak detection apparatus suitable for detecting liquid leakage and a leak detection method using the same.

  When liquid leaks from a container filled with water or the like to the outside, or when liquid leaks from the outside into the container, in order to stop the leak by repairing, first detect the leak, Need to be identified.

  Japanese Patent Application Laid-Open No. H10-228667 is known as performing such leakage detection and leakage location identification using ultrasonic waves. Patent Document 1 discloses a technique in which an ultrasonic sensor is immersed in water, bubbles are generated in water by a bubble generator, and reflection of ultrasonic waves by the bubbles is measured. Then, the position of the center of gravity of the bubble is obtained from the reflected wave from the measured bubble, the movement of the position of the center of gravity of the bubble is detected, the flow of liquid such as water in the container is estimated, and the leak location in the container Is to identify.

JP2013-113628A

  However, in the configuration of Patent Document 1, a reflected wave from a target bubble may be buried in a reflected wave from a structure such as a side wall in the container, which may make it difficult to detect leakage and identify a leakage location. is there. That is, there is room for improvement in improving S / N when leakage detection is performed using ultrasonic waves.

  Therefore, the present invention makes it possible to detect a tracer such as bubbles or fine particles in a liquid such as water with high accuracy using ultrasonic waves, thereby providing a highly reliable ultrasonic leak detection device and a leak using the same. It is to provide a detection method.

To solve the above problems, an ultrasonic leak detecting apparatus of the present invention, the ultrasonic sensor is arranged to be immersed in the liquid in the container, or bubbles or fine particles to be introduced into the liquid in the container Ultrasonic waves are transmitted from the ultrasonic sensor at a predetermined transmission time interval and a predetermined number of transmissions, and the number of transmissions in a desired ultrasonic wave propagation time is changed according to a change in received waveform over time. A signal processing unit that generates an orthogonal waveform based on an amplitude value of a corresponding received waveform, and a display unit that displays the generated orthogonal waveform or displays the orthogonal waveform and a change over time of the received waveform together. Features.

Further, leak detection method of the present invention, from the ultrasonic sensor is arranged to be immersed in the liquid in the vessel, the bubbles or fine particles or Ranaru tracer is introduced into the liquid in the vessel, the ultrasonic A method of detecting leakage of a liquid using a received waveform that can be transmitted, the step of transmitting ultrasonic waves from the ultrasonic sensor to the tracer at a predetermined transmission time interval and a predetermined number of transmissions, and the ultrasonic wave An orthogonal waveform generating step for generating an orthogonal waveform based on an amplitude value of the received waveform corresponding to each of the number of times of transmission in a desired ultrasonic wave propagation time according to a time-dependent change in the received waveform obtained by transmitting the waveform, and the generated orthogonal waveform Or a display step of displaying the change over time of the orthogonal waveform and the reception waveform on a display unit.
The

  According to the present invention, a tracer such as bubbles or fine particles in a liquid such as water can be detected with high accuracy using ultrasonic waves, and a highly reliable ultrasonic leak detector and a leak using the same A detection method can be realized.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a block diagram of the principal part of the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing of a use condition including the tracer injection | throwing-in apparatus which comprises the ultrasonic type leak detection apparatus which concerns on one Embodiment of this invention. It is other explanatory drawing of a use condition including the tracer injection | throwing-in apparatus which comprises the ultrasonic type leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the transmission and reception timing of the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the display form of the received waveform displayed on the display part of the ultrasonic type leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the other display form of the received waveform displayed on the display part of the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the ultrasonic sensor which comprises the ultrasonic type leak detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the ultrasonic sensor which comprises the ultrasonic type leak detection apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the shape measurement of the structure by the ultrasonic sensor which comprises the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the condition of the leak detection by the ultrasonic sensor which comprises the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the measurement of the flow velocity by the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing of the orthogonal waveform used for the flow velocity measurement by the ultrasonic leak detection apparatus of Example 1 which concerns on one Example of this invention. It is a figure for demonstrating the orthogonal waveform which shifted the time used for the flow velocity measurement by the ultrasonic leak detection apparatus of Example 1. FIG. It is a figure which shows the display form of the orthogonal waveform displayed on the display part of the ultrasonic leakage detection apparatus of Example 1. FIG. 3 is a flowchart illustrating a leak detection process of the ultrasonic leak detection apparatus according to the first embodiment. It is a figure which shows the display form of the orthogonal waveform displayed on the display part of the ultrasonic leakage detection apparatus of Example 2 which concerns on the other Example of this invention. It is a block diagram of the principal part of the ultrasonic leak detection apparatus of Example 2. 6 is a flowchart illustrating a leak detection process of the ultrasonic leak detection apparatus according to the second embodiment. It is a figure for demonstrating the reliable propagation time area | region obtained from the statistics of the correlation result by the ultrasonic leak detection apparatus of Example 3 which concerns on the other Example of this invention. 10 is a flowchart illustrating a leak detection process of the ultrasonic leak detection apparatus according to the third embodiment.

  Hereinafter, in this specification, the tracer is a general term for bubbles or fine particles, and as fine particles, for example, a flocculant such as silicon oxide, alumina (aluminum oxide), ferric chloride, and the like or dissolved in water in the flocculant. A floc or the like in which the organic substance contained is captured and formed is used. Regarding the particle size of the fine particles, the specific gravity with the medium filled in the container, for example, water, that is, the liquid does not float on the liquid surface and does not settle (precipitate) on the bottom surface of the container. What is necessary is just to select the size which can be moved by the convection of water suitably.

  In FIG. 1, the block diagram of the principal part of the ultrasonic leak detection apparatus which concerns on one Embodiment of this invention is shown. The ultrasonic leak detection apparatus 1 includes an ultrasonic sensor 10, an ultrasonic transmission / reception unit 11, a display unit 12, a signal processing unit 13, and a tracer input device 23 described later.

  The ultrasonic transmission / reception unit 11 includes a transmission unit 11A, a reception unit 11B, a control unit 11C, and a storage unit 11D, and the control unit 11C controls the whole. The transmission unit 11A is connected to the ultrasonic sensor 10 and controlled by the control unit 11C, and at a constant time interval (transmission time interval ΔTp, for example ΔTp = 0.05 sec) and the number of transmissions (for example, Np times, Np = 256). Send ultrasonic waves. Here, the ultrasonic sensor 10 is a two-dimensional sensor array in which piezoelectric elements (not shown) are arranged, for example, in a two-dimensional manner. The ultrasonic sensor 10 vibrates according to the transmission frequency from the transmitter 11A, and ultrasonic waves are transmitted from the ultrasonic sensor 10. The reflected ultrasonic wave (received wave) is transmitted by the ultrasonic sensor 10 and taken into the receiving unit 11B. The reflected wave captured by the receiving unit 11B is converted into digital data at a certain time interval (sampling interval (sampling period) ΔTs, for example, ΔTs = 0.2 μsec) and stored in the storage unit 11D.

  The signal processing unit 13 includes an orthogonal waveform generation unit 13A and a correlation processing unit 13B. The orthogonal waveform generation unit 13A arranges the orthogonal waveforms by arranging the amplitude values of the reception waveforms having the same propagation time among the reception waveforms stored in the storage unit 11D in the order of the transmission time of the ultrasonic waves. Generate. The orthogonal waveform is generated every propagation time of the received waveform. When the sampling interval ΔTs is 0.2 μsec and the number Ns of digital data obtained is Ns = 5000 points (1 msec), 5000 orthogonal waveforms are generated. When the medium is water, the ultrasonic sound velocity is about 1500 m / sec. Therefore, the reciprocating distance in 1 msec is 1500 mm (750 mm in one way). Therefore, the orthogonal waveform generated for each propagation time can be converted into an orthogonal waveform for each propagation distance using the speed of sound. Here, the quadrature waveform at a certain propagation time generated by the quadrature waveform generation unit 13A is stored in the storage unit 11D.

  The correlation processing unit 13B performs autocorrelation processing of the first orthogonal waveform with a certain propagation time or the first orthogonal waveform with a certain propagation time and, for example, the propagation time of the received waveform n × ΔTs (where n is an integer). A cross-correlation process is performed on second orthogonal waveforms that are different from each other. For example, when n = 0, autocorrelation occurs, and the number of correlation results, that is, the number of autocorrelation processing results, matches the number of ultrasonic transmissions Np. In the case of n = 1, there is a cross-correlation between a first orthogonal waveform having a certain propagation time and a second orthogonal waveform having a propagation time different by ΔTs from the propagation time of the first orthogonal waveform. , That is, the number of cross-correlation processing results is less than the number of ultrasonic transmissions and is Np−1.

  The first orthogonal waveform of propagation time j × ΔTs is φj (t), and the second orthogonal waveform of propagation time k × ΔTs is φk (t). Here, the argument t is t = i × ΔTp (i = 0 to Np−1) because it is determined by the ultrasonic transmission time interval ΔTp and the number of transmissions Np.

  The cross-correlation processing result Rjk (τ) between the first orthogonal waveform φj (t) and the second orthogonal waveform φk (t) can be calculated, for example, by the following equation (1). Here, τ is a parameter representing a time difference in the transmission time t. In the equation (1), the function E means an ensemble average, the function C (Cj, Ck, Cjk) means a correlation coefficient, and the function R (Rjk) means a normalized correlation coefficient.

  Further, the control unit 11C constituting the ultrasonic transmission / reception unit 11 shown in FIG. 1, the orthogonal waveform generation unit 13A and the correlation processing unit 13B constituting the signal processing unit 13 read and read various programs stored in the ROM. This is realized by a processor such as a CPU that executes the program.

  Here, FIG. 2 shows a use state of the ultrasonic leak detection apparatus 1 having the tracer input device 23 according to an embodiment of the present invention. As shown in FIG. 2, the container 21 represents a situation in which a liquid such as water is accommodated as a medium. The amount of the medium accommodated in the container 21 may be either an amount that fills almost the entire container 21 or an amount that partially fills the container 21. The medium may be a substance having a fluid property, such as a liquid, but in the following, water will be described as an example.

  As shown in FIG. 2, the ultrasonic leak detection apparatus 1 according to the present embodiment has an access jig 22 </ b> A that can hold an ultrasonic sensor 10 at its tip and can be positioned at a desired position in water, and a tracer input device 23. Is provided with an access jig 22B that can be held at its tip and positioned at a desired position in water. As the access jigs 22A and 22B, for example, an articulated manipulator or a pole is used. In FIG. 2, the case where the hole 25 of the wall surface which is a leak location is formed in the bottom face of the container 21 which accommodates the water which is a medium is shown. The ultrasonic sensor 10 passes through the liquid level 26 from the upper part of the container 21 by the access jig 22 </ b> A and is positioned near the hole 25 on the wall surface formed on the bottom surface of the container 21. Similarly, the access jig 22 </ b> B causes the tracer charging device 23 to pass through the liquid level 26 from the top of the container 21 and is positioned between the hole 25 on the wall surface and the ultrasonic sensor 10. The tracer throwing device 23 throws a certain amount of the tracer 24 into the water for a certain period. Here, the tracer 24 is a bubble or a fine particle as described above, and serves as a reflection source for the ultrasonic wave transmitted from the ultrasonic sensor 10. That is, the tracer 24 reflects the ultrasonic waves, and the reflected waves are taken in the receiving unit 11B shown in FIG. 1 through the ultrasonic sensor 10 as received waves.

  FIG. 3 shows another usage state of the ultrasonic leak detection apparatus 1 having the tracer input device 23 according to the embodiment of the present invention. As shown in FIG. 3, a moving device loading opening 31 for inserting the moving devices 32 </ b> A and 32 </ b> B is formed on the upper surface of the container 21. FIG. 3 shows a case where a hole 25 in the wall surface, which is a leaking portion, is formed in the lower part of the side surface of the container 21 that stores water as the medium. The moving device 32A on which the ultrasonic sensor 10 is mounted is loaded into the container 21 through the moving device loading opening 31. The moving device 32 </ b> A includes, for example, a thruster and a crawler (not shown), and is configured to be able to move in water or move along the wall surface of the container 21. FIG. 3 shows a state in which the moving device 32 </ b> A navigates the liquid level 26 and is positioned near the hole 25 on the wall surface along the side surface of the container 21. Similarly, the moving device 32B on which the tracer insertion device 23 is mounted is shown as being positioned on the bottom surface of the container 21 and facing the hole 25 on the wall surface. The tracer throwing device 23 throws a certain amount of the tracer 24 into the water for a certain period. Here, the tracer 24 is a bubble or a fine particle as described above, and serves as a reflection source for the ultrasonic wave transmitted from the ultrasonic sensor 10. That is, the tracer 24 reflects the ultrasonic waves, and the reflected waves are taken in the receiving unit 11B shown in FIG. 1 through the ultrasonic sensor 10 as received waves.

  In FIGS. 2 and 3, it is desirable that the tracer input device 23 be positioned in the vicinity of the ultrasonic sensor 10. Further, when the tracer 24 to be introduced into the water from the tracer introduction device 23 is a fine particle, it is not always necessary to immerse the tracer introduction device 23 in the water. The tracer 24 is directed from the gas phase in the container 21 toward the liquid surface 26. You may position so that it may throw in. In any case, the ultrasonic sensor 10 is positioned so that the whole is immersed.

  FIG. 4 shows the transmission and reception timings of the ultrasonic leak detection apparatus 1. As shown in the upper diagram of FIG. 4, the transmission unit 11 </ b> A constituting the ultrasonic transmission / reception unit 11 has a certain period according to a certain time interval (transmission time interval ΔTp) and the number of transmissions Np according to a command from the control unit 11 </ b> C. The transmission pulse 41 is output to the ultrasonic sensor 10. Here, as the waveform of the transmission pulse 41, a spike pulse, a rectangular wave, a sine wave, or the like is used.

4, the ultrasonic wave transmitted from the ultrasonic sensor 10 in synchronization with the transmission pulse 41 includes the reflected wave from the tracer 24 and the like in the container 21, and the received waveform 42 is A plurality of pieces are repeatedly received and converted into digital data by the receiving unit 11B. In the lower diagram of FIG. 4, the reception waveform obtained in synchronization with the J + 2th transmission pulse 41 corresponding to the Jth to J + 2th transmission times corresponding to the Jth transmission frequency (transmission frequency), the Jth to J + 2th. The received waveform 42 of the eye is shown with time on the horizontal axis and amplitude on the vertical axis. Conversion of the received wave from analog data to digital data in the receiving unit 11B is performed by a sampling interval (sampling period) ΔTs and the number of data points Ns. The reciprocal of the sampling interval ΔTs is the sampling frequency fs. From the Nyquist theorem, fs needs to be at least twice (fs ≧ 2 × f0) with respect to the center frequency f _{0 of the} ultrasonic signal to be measured. is there. For example, when the center frequency of the reception waveform 42 is 2 MHz, for example, the sampling frequency fs may be 5 MHz and the sampling interval may be 0.2 μsec.

  FIG. 5 is a diagram illustrating a display form of a received waveform displayed on the display unit 12 of the ultrasonic leak detection apparatus 1. For example, as shown in FIG. 5, the display unit 12 displays reception waveforms 42 at the number of receptions (from the (J−1) th time to the (J + 1th) time) corresponding to the number of transmission times (from the (J−1) th time to the (J + 1) th time). The received waveform 42 is displayed on the screen of the display unit 12 with the propagation time on the horizontal axis and the amplitude on the vertical axis. Note that the horizontal axis may be converted to a propagation distance using the speed of sound of an ultrasonic wave that travels in water, which is a medium, instead of the propagation time. The vertical axis may display the absolute value of the amplitude.

  FIG. 6 is a diagram showing another display form of the received waveform displayed on the display unit 12 of the ultrasonic leak detection apparatus 1. As shown in the lower diagram of FIG. 6, the amplitude value of the received waveform corresponding to the number of times of ultrasonic transmission (transmission frequency) (for example, the Jth time) is color-coded by gradation display or color using a color bar or the like. If it is displayed and the magnitude of the amplitude value for each propagation time is represented by the color, the received waveform can be displayed in a two-dimensional map, for example, with the number of transmissions on the vertical axis and the propagation time on the horizontal axis. it can. FIG. 6 shows a case where the transmission time interval ΔTp is the number of transmissions (number of transmissions) Np, and among the reception waveforms corresponding to the number of transmissions from the first time to the Np time, reception is performed for the J−1th time, the Jth time, and the J + 1th time. The waveform shows an example in which the amplitude value for each propagation time is displayed in gradation using a color bar. In this way, the map-like received waveform shown in the lower diagram of FIG. 6 is displayed on the screen of the display unit 12. In this map-like received waveform, if the J-th received waveform is designated by the user, the J-th received waveform (vertical axis: amplitude, horizontal axis: propagation time) shown in the upper diagram of FIG. A pop-up is displayed on the screen of the display unit 12. When displaying a two-dimensional map-like received waveform, the vertical axis may be replaced with the number of transmissions, for example, the transmission time or the number of receptions or the reception time. Further, the horizontal axis may be a propagation distance instead of the propagation time.

  The ultrasonic sensor 10 transmits and receives ultrasonic waves in water, which is a medium filling the container 21. Although the ultrasonic sensor 10 can be configured by a single piezoelectric element, for example, as shown in FIGS. 7 and 8, an ultrasonic array sensor 33A configured by a plurality of piezoelectric elements 33B may be used. . When the piezoelectric elements 33B constituting the ultrasonic array sensor 33A are uniaxially arranged (when arranged in a one-dimensional manner), three-dimensional scanning is possible by combining with mechanical scanning as shown in FIG. In addition, as shown in FIG. 8, when the ultrasonic array sensor 33A is configured by two-dimensionally arranging the piezoelectric elements 33B, it is possible to electronically perform three-dimensional scanning.

  FIG. 9 illustrates a procedure for measuring the shape of a structure when an array sensor is used as the ultrasonic sensor 10. For example, a delay addition method is used as a method of visualizing underwater, which is a medium, using an array sensor.

  The delay addition method is also referred to as a phased array method, an electronic scanning method, or an electronic scanning method. For example, a probe in which a plurality of ultrasonic generating elements made of piezoelectric elements are arranged in an array, that is, a so-called ultrasonic array sensor 33A. And applying an electrical signal that triggers the generation of ultrasonic waves to each element of the ultrasonic array sensor 33A with a predetermined time delay, and superimposing the ultrasonic waves generated from each element to form a composite wave. The conditions such as the transmission angle and reception angle of ultrasonic waves to the object to be inspected, the transmission position and reception position, or the position where the combined waves interfere with each other to strengthen the energy, that is, the focal position, etc. It can be changed with. For example, with respect to the amplitude A (t, θi) of the signal received from the direction of the angle θi at a certain sensor position Xk, the propagation distance W is obtained from the product of the propagation time t and the speed of sound c, and the angle θi with reference to the sensor position Xk. By setting A (t, θi) as the pixel value of the point at the distance W and changing θi, a fan-shaped image is formed, or θi is fixed and the sensor position Xk is moved to move in parallel. It is a method for creating a total ultrasonic transmission / reception image that forms a quadrilateral image.

  For imaging, as shown in FIG. 9, at a transmission / reception position Xk, for a received waveform A (t; θi) 44 that has an ultrasonic propagation path 43 propagating in the direction θi, a certain propagation time t From the amplitude value 44B and the angle θi at, the image of the ultrasonic measurement result is imaged in the sector scan display range 46 by visualizing the pixel value corresponding to the magnitude of the amplitude value while changing θi. it can. As the shape changing portion, for example, an area 45 (the entire reflected wave from the shape) 45 is visualized by the amplitude value of the reflected wave from the surface of the pipe 27. The boundary of this region 45, that is, the surface of the pipe 27 is visualized as the boundary 45A of the ultrasonic image as the rise of the amplitude of the received waveform A (t; θi) (start position of the reflected wave portion from the shape) 44A. The

  In the case of visualization by the delay addition method, for example, a cross-sectional image on a certain plane can be formed by the above procedure. Therefore, as shown in FIG. 7, the supersonic wave generated from the ultrasonic array sensor 33A by mechanical scanning is used. By moving the surface on which the sound wave propagates in a direction including a component orthogonal to the surface, a plurality of planar images can be formed, and a stereoscopic image can be formed. Alternatively, as shown in FIG. 8, the piezoelectric elements 33B forming the ultrasonic array sensor 33A are two-dimensionally arranged to perform electronic scanning three-dimensionally and similarly to form a plurality of planar images, An image can be formed.

For example, as shown in FIG. 9, when imaging the surface of the pipe 27, which is a reflector (structure), using the delay-and-sum imaging method, the horizontal axis represents time (or distance) and the vertical axis represents amplitude. A fan-shaped cross-sectional view is drawn from the amplitude value A (t; θi) of the received waveform propagating in a specific direction (incident angle θi) and the propagation direction (incident angle θi). In the fan-shaped display, pixel values are visualized as pixels in correspondence with monochrome or color color bars.
If attention is paid to a certain angle θi, the rising point (start position of the reflection part from the shape) 44A of the received waveform 44, the amplitude value A (t; θi) of the propagation time t, the magnitude of the amplitude value A in color, When converted into grayscale values and displayed as a fan-shaped image, the reflected wave from the structure such as the pipe 27 is displayed as a wide distribution as the region 45. The distance from the ultrasonic sensor 10 to the pipe 27 can be measured with an image 44 </ b> B corresponding to the rising of the received waveform 44. As described above, the outer shape of the structure having a possibility of leakage can be visualized by ultrasonic waves.

  In order to perform leakage detection using ultrasonic waves, it is necessary to capture the flow of the minute tracer 24 (bubbles or fine particles) flowing along with the leakage in the water as the medium to be measured. FIG. 10 is a diagram for explaining a state of leak detection by the ultrasonic sensor 10 constituting the ultrasonic leak detection apparatus 1. As shown in FIG. 10, on the wall surface 21 </ b> A having the container 21 that stores the water as the medium, the pipe 27 arranged to protrude into the container 21 and the root of the pipe 27 are fixed to the wall surface 21 </ b> A of the container 21. A double-pipe structure 28 is provided. If it is assumed that leakage has occurred in the double-pipe structure portion 28, the tracer 24 introduced into the water in the container 21 from the tracer introduction device 23 (not shown) is a leakage point as time passes. The flow along the tracer moving direction 29 moves from the tracer 24 </ b> A to the tracer 24 </ b> B by the flow accompanying leakage to the heavy pipe structure 28. Here, the flow rate of water (leakage water) that is a medium flowing to the double pipe structure 28 that is assumed to be a leak point is a very gentle flow of about 1 mm / sec to 100 mm / sec. As shown in FIG. 10, the ultrasonic sensor 10 held at the tip of the access jig 22 </ b> A is positioned in the vicinity of the pipe 27 and the double pipe structure 28. As shown in FIG. 9, after grasping the shape of the double pipe structure portion 28 that is assumed to be a leak location, the water flow of the leaked water in the vicinity of the double pipe structure portion 28 is measured. As shown in FIG. 10, the reflected wave from the tracer 24 </ b> A group at a certain time and the tracer 24 </ b> B group after a predetermined time has passed through the ultrasonic sensor 10 to form an ultrasonic wave that constitutes the ultrasonic leak detection apparatus 1. The water flow of the leaked water is measured by detecting it as a received waveform with the receiving unit 11B of the sound wave transmitting / receiving unit 11.

  Here, the flow rate measurement of leaked water by the ultrasonic leak detector 1 will be described with reference to FIG. FIG. 11 schematically shows changes in the received waveform obtained from the underwater tracer 24 as a medium when ultrasonic waves are transmitted a plurality of times at a constant transmission time interval ΔTp. In FIG. 11, for easy understanding, the number of transmissions (number of transmissions) Np output from the control unit 11 </ b> C to the transmission unit 11 </ b> A indicates the number of transmissions up to the fifth, and reception corresponding to each number of transmissions. The waveform is shown. As described above, the transmission time interval ΔTp is, for example, 0.05 sec, and the reflected wave from the trace 24 taken into the receiving unit 11B is digital data at the sampling interval (sampling period ΔTs, for example, ΔTs = 0.2 μsec). Therefore, as shown in the right diagram of FIG. 11, received waveforms corresponding to the number of times of ultrasonic transmission (first to fifth) transmitted from the ultrasonic sensor 10 are obtained. As shown in the left diagram of FIG. 11, when the flow of water accompanying leakage (flow of leaked water) is formed in a direction away from the ultrasonic sensor 10, the underwater tracer 24 that is a medium also changes to the flow of leaked water. Then, move away from the ultrasonic sensor 10. The received waveform including the reflected wave by the tracer 24 has a tendency that the propagation time is gradually increased as shown in the right figure. In FIG. 11, for convenience of explanation, the change in the received waveform is emphasized, but actually, a plurality of tracers 24 are included, the intensity of reflected waves from the tracers 24 is weak, For this reason, it is assumed that it is difficult to directly observe the temporal change itself of the received waveform.

  However, in the ultrasonic leak detection apparatus 1 according to the present embodiment, the orthogonal wave generation unit 13A provided in the signal processing unit 13 determines the reflected wave for each transmission number obtained from the tracer 24, that is, the number of transmissions. Among the corresponding received waveforms, for example, the orthogonal waveform is generated by arranging the amplitude values of the received waveforms having the same propagation time in the order of the number of transmissions. Then, by the correlation processing unit 13B provided in the signal processing unit 13, the autocorrelation processing of the first orthogonal waveform of a certain propagation time or the first orthogonal waveform of a certain propagation time and the first orthogonal waveform By performing the cross-correlation process with the second orthogonal waveform whose propagation time is different from the propagation time by ΔTs, for example, the S / N of the received waveform detection from the tracer 24 can be improved. Thereby, since the movement direction or movement location of the tracer 24 can be specified, the leakage detection and the leakage location can be specified with high accuracy.

  Hereinafter, with reference to the drawings, an embodiment will be described mainly with respect to the orthogonal waveform generation unit 13A and the correlation processing 13B constituting the signal processing unit 13.

  FIG. 12 is an explanatory diagram of orthogonal waveforms used in the flow velocity measurement by the ultrasonic leak detection apparatus 1 according to the first embodiment of the present invention. The ultrasonic leak detection device 1 having the tracer input device 23 of the present embodiment has the same configuration as shown in FIGS. 1 to 3 and FIGS. 7 to 10.

  As shown in FIG. 12, the orthogonal waveform generation unit 13A of the signal processing unit 13 included in the ultrasonic leak detection apparatus 1 arranges the reception waveforms for each transmission time interval ΔTp, that is, in order of the number of transmissions. Then, the orthogonal waveform generation unit 13A extracts the amplitude value of the received waveform corresponding to each number of transmissions having a certain propagation time t, and at the propagation time t with the number of transmissions or the transmission time as an axis as shown on the right side of FIG. Generate an orthogonal waveform. In FIG. 12, for the sake of convenience of explanation, the transmission frequency interval (transmission time interval ΔTp) is widened and only the first to fifth transmission times are shown, but in practice, as described above. ΔTp is set to 0.05 sec, for example, and the interval of the number of transmissions is narrow. Accordingly, the amplitude value of the received waveform corresponding to each number of transmissions with a certain propagation time t at the time of generating the orthogonal waveform is larger than that shown in FIG. 12, and in particular, the orthogonal waveform at a certain propagation time t is not required to perform interpolation calculation. It can be generated. Note that by generating an orthogonal waveform at a certain propagation time t as described above, there is an effect of subtracting a minute time change of the received waveform, so that the minute change can be emphasized. As described above, the flow rate of the leaked water is, for example, a very slow flow (low speed) of about 1 mm / sec to 100 mm / sec. Naturally, the movement of the tracer 24 that moves with the flow of the leaked water. The speed will be low as well. However, according to the present embodiment, it is possible to reliably detect the tracer 24 that moves at low speed in the water, which is the medium, by generating an orthogonal waveform.

  FIG. 13 is an explanatory diagram of an orthogonal waveform with a shifted time used for flow velocity measurement by the ultrasonic leak detection apparatus 1 of the present embodiment. In FIG. 12, the amplitude value of the received waveform of each transmission count in the same propagation time t is extracted to generate an orthogonal waveform. On the other hand, as shown in FIG. 13, the orthogonal waveform generation unit 13A extracts the amplitude value of the received waveform corresponding to each number of transmissions by delaying the propagation time by a predetermined equal interval so as to be linear with the number of transmissions. To do. That is, the amplitude value of the received waveform in the propagation time shifted at a predetermined time interval (equal interval) for each transmission count is extracted. Then, using the extracted amplitude value, as shown in the right diagram of FIG. 13, an orthogonal waveform in the shifted propagation time with the number of transmissions or transmission time as an axis is generated. Although FIG. 13 shows the most extreme case, it can be seen that there is no vibration in the shifted orthogonal waveform, and the change is a direct current change. For this reason, for example, when the waveform of the orthogonal waveform is fast and the sampling interval of the orthogonal waveform exceeds the limit of the Nyquist theorem, the propagation time of the received waveform is changed linearly with the number of transmissions of the orthogonal waveform sampling. However, by generating a shifted orthogonal waveform, it becomes possible to evaluate the flow velocity beyond the theoretical limit.

  In FIG. 14, the display form of the orthogonal waveform displayed on the display part 12 of the ultrasonic leak detection apparatus 1 which concerns on a present Example is shown. Based on the reception waveform at the number of receptions corresponding to the number of transmissions stored in the storage unit 11D by the control unit 11C, as shown in the lower diagram of FIG. 14, the amplitude value is gradation or color-coded with a color bar or the like, and the display unit 12 On the screen. The gray value in the gradation display or each color in the color-coded display corresponds to the magnitude relationship of the amplitude value for each propagation time. Specifically, the vertical axis represents the number of transmissions (transmissions) Np at the transmission time interval ΔTp, and the horizontal axis represents the propagation time, and the two-dimensional map is displayed. The lower diagram of FIG. 14 illustrates a case where the received waveform corresponding to the number of times of transmission J−1 to J + 1 is displayed in gradation with a color bar for the amplitude value for each propagation time. In FIG. 14, for the sake of convenience of explanation, only J-1 to J + 1 times are shown. However, on the actual screen of the display unit 12, all received waveforms corresponding to the number of transmission times 1 to Np are shown. Displayed in a two-dimensional map. In this two-dimensional map, if a desired propagation time t is designated by the user with a cursor or pointer, the control unit 11C displays the transmission time on the horizontal axis and the vertical axis as shown in the upper diagram of FIG. And control so that the orthogonal waveform at the propagation time t pops up on the screen of the display unit 12. Here, the orthogonal waveform at the propagation time t shown in the upper diagram of FIG. 14 exemplifies a case similar to the orthogonal waveform shown on the right side of FIG. 12 described above. The orthogonal waveform stored in the storage unit 11 </ b> D of the transmission / reception unit 11 is read by the control unit 11 </ b> C and popped up on the screen of the display unit 12. The orthogonal waveform pop-up displayed in this way is not limited to the orthogonal waveform shown in FIG. 12, but the reception time corresponding to each number of transmissions is obtained by delaying the propagation time by a predetermined equal interval so as to be linear with the number of transmissions. It is good also as an orthogonal waveform shown in FIG. 13 produced | generated by extracting the amplitude value. In the display of orthogonal waveforms, the horizontal axis may be replaced with the transmission time and the number of transmissions.

  Next, the leak detection process by the ultrasonic leak detector 1 of the present embodiment will be described. FIG. 15 is a flowchart of the leakage detection process.

  First, as shown in FIG. 2, the ultrasonic sensor 10, the tracer throwing device 23 and the like are put into a medium such as water in the container 21 by the access jigs 22A and 22B (step S10). Thereafter, the ultrasonic sensor 10 is moved by the access jig 22A and / or the tracer feeding device 23 is moved by the access jig 22B, and the shape changing portion in the container 21 (for example, the hole 25 on the wall surface shown in FIG. 2). Explore. At this time, the shape of the reflector is measured as shown in FIG. 9 by transmitting ultrasonic waves and receiving a reflected wave from the structure that is a reflector in the container 21 by the ultrasonic sensor 10 ( Step S11).

  When a shape change portion having a possibility of leakage is detected in the container 21 by the shape measurement in step S11, the movement of the ultrasonic sensor 10 by the access jig 22A and the tracer input device 23 by the access jig 22B are detected. Stop moving. As a result, the ultrasonic sensor 10 and the tracer input device 23 are positioned and fixed to the detected shape change portion (step S12).

  Subsequently, a predetermined amount of the tracer 24 is input into a medium such as water from the tracer input device 23 for a predetermined period. In addition, the transmission unit 11 </ b> A constituting the ultrasonic transmission / reception unit 11 outputs a transmission pulse having a constant period to the ultrasonic sensor 10 according to a command from the control unit 11 </ b> C. Here, the transmission pulse of a fixed period output from the transmission unit 11A to the ultrasonic sensor 10 is, for example, the transmission pulse 41 shown in FIG. That is, the transmission unit 11A generates a transmission pulse corresponding to the transmission time interval ΔTp and the number of transmissions (number of transmissions) Np set by the control unit 11C. The ultrasonic sensor 10 transmits the ultrasonic wave a plurality of times in the vicinity of the shape changing portion that may leak at the transmission time interval ΔTp corresponding to the transmission pulse (step S13). The control unit 11C stores (records) in the storage unit 11D a plurality of received waveforms corresponding to the number of times of ultrasonic transmission, which are obtained via the ultrasonic sensor 10 and the reception unit 11B constituting the ultrasonic transmission / reception unit 11. (Step S14). In step S15, the orthogonal waveform generation unit 13A constituting the signal processing unit 13 reads the reception waveform corresponding to the number of transmissions stored in the storage unit 11D, generates the orthogonal waveform shown in FIG. Stored in the unit 11D.

  Next, the correlation processing unit 13B constituting the signal processing unit 11 calculates the autocorrelation process of the orthogonal waveform generated by the orthogonal waveform generation unit 11A in step S15 (step S16). Here, the autocorrelation processing of the orthogonal waveform can be obtained by calculating with k = j in the normalized correlation coefficient Rjk (τ) in the above equation (1). By performing autocorrelation processing in this way, even when a noise component (harmonic component) such as white noise is included in the received waveform, without using an analog circuit such as a low-pass filter, White noise can be removed. As shown in FIG. 12, an ideal orthogonal waveform that does not include a noise component is oscillating and has a high correlation. Therefore, by removing the white noise component by autocorrelation processing, It is possible to emphasize the change in the reflected wave from the tracer 24 that is a reflector, that is, the vibration of the orthogonal waveform. As a result, the tracer 24 input from the tracer input device 23 can be detected with high accuracy in the vicinity of the shape changing portion having the possibility of leakage. Moreover, based on the vibration (frequency) of the orthogonal waveform produced | generated by the reflected wave from the tracer 24 obtained, the moving speed of the tracer 24 which moves underwater in the container 21 with leakage of media, such as water, is measured. As a result, it becomes possible to obtain the flow rate of the leaked water.

Next, the control unit 11C determines whether or not the orthogonal waveform autocorrelation processing by the correlation processing unit 13B has been executed a set number of times in step S16 (step S17). Here, the set number of times is the number of transmissions (number of times of transmission) Np set by the control unit 11C together with the transmission time interval ΔTp used for generation of transmission pulses transmitted from the transmission unit 11A to the ultrasonic sensor 10. This is because, as described above, the number of autocorrelation processing results obtained by the correlation processing unit 13B matches the number of ultrasonic transmissions transmitted from the ultrasonic sensor 10. Therefore, the control unit 11C determines whether or not the number of autocorrelation processing results obtained from the correlation processing unit 13B has reached Np, which is the set number of times. As a result of the determination, if the number of autocorrelation processing results has not reached Np, the process returns to step S13, and the processing up to step S17 is repeated. If the determination result reaches Np, the process proceeds to step S18.

  In step S <b> 18, the control unit 11 </ b> C controls the readout waveform, the orthogonal waveform, the autocorrelation processing result, and the like stored in the storage unit 11 </ b> D to be read and displayed on the screen of the display unit 12. Here, the display form on the screen of the display unit 12 includes the two-dimensional map display of the received waveform shown in FIG. 14, the pop-up display of the orthogonal waveform at the propagation time t specified by the user, and Np autocorrelations. The processing result is displayed.

  Following step S18, in step S19, the control unit 11C stores the presence / absence of leakage in the shape changing unit in the container 21 and the position of the shape changing unit, which have obtained the autocorrelation processing result, in the storage unit 11D, Return to step S11. That is, since the leak location is not limited to one location, the process returns to step S11 to search for the next shape change portion in the container 21. In addition, since it is difficult to specify the moving direction of the tracer 24 accompanying the flow of leaked water in the container 21 only by the autocorrelation processing result of the orthogonal waveform, the S / N is improved and detected with high accuracy. For the tracer 24 in a medium such as water in the container 21, for example, as shown in Patent Document 1, the position of the center of gravity of the group of tracers 24 or the movement direction of the entire region in which the tracer 24 is diffused with movement is detected. Thereby, it can be determined whether the shape change part in the said container 21 is a leak location. That is, the presence or absence of leakage can be determined.

  In steps S10 to S12 described above, the moving devices 32A and 32B shown in FIG. 3 may be used instead of the access jigs 22A and 22B.

In addition, the case where the orthogonal waveform generation unit 13A generates the orthogonal waveform by extracting the amplitude value of the reception waveform at each transmission count in the same propagation time t as illustrated in FIG. 12 in step S15 has been described. However, it is not limited to this. For example, the orthogonal waveform generation unit 13A extracts the amplitude value of the received waveform in the propagation time shifted at a predetermined time interval (equal interval) for each transmission number so that the transmission number is linear. Then, the orthogonal waveform generation unit 11A may be configured to generate an orthogonal waveform in the shifted propagation time with the number of transmissions or the transmission time as an axis, as shown in FIG. 13, using these extracted amplitude values. good. By using the orthogonal waveform in the shifted propagation time in this way, it is assumed that the flow rate of the medium such as water due to the leaked portion generated in the container 21 with respect to the transmission time interval ΔTp of the ultrasonic wave, that is, the leaked water Even when the change in the flow rate is too small, or conversely, when the change in the flow rate of the leaked water is too large, the amount of change in the flow rate can be virtually shifted. This makes it possible to visualize whether or not the tracer 24 is sufficient for measuring the moving speed of the tracer 24, that is, measuring the flow rate of leaked water, and further improving the accuracy of leak detection. It becomes possible.

  According to the present embodiment, it is possible to improve the S / N ratio of detection of a received waveform from the tracer 24 contained in a medium such as water in the container 21 that may leak.

  Further, by specifying the moving direction of the tracer 24, it is possible to improve the leakage detection accuracy and specify the leakage location.

  FIG. 16 shows a display form of orthogonal waveforms displayed on the display unit of the ultrasonic leak detection apparatus 1 ′ according to the second embodiment of the present invention. In the first embodiment, the correlation processing unit 13B configuring the signal processing unit 13 is configured to perform autocorrelation calculation based on the orthogonal waveform generated by the orthogonal waveform generating unit 13A, whereas in the present embodiment, the signal processing unit 13 differs in that it is configured to perform cross-correlation processing based on the generated orthogonal waveform.

  In this embodiment, based on the received waveform at the number of receptions corresponding to the number of transmissions stored in the storage unit 11D by the control unit 11C, the vertical axis is the time difference (τ), the horizontal axis is the propagation time, and the amplitude value of the received waveform FIG. 16 shows a state in which gradation display or color-coded display is performed with a color bar or the like. The time difference (τ) shown on the vertical axis indicates the time difference at each transmission count for each transmission time interval ΔTp with respect to the vertical transmission count shown in the lower diagram of FIG. Yes. The horizontal axis is the same as the propagation time shown in the lower diagram of FIG. In this embodiment, since the correlation processing unit 13B described later calculates the cross-correlation processing, if the propagation time t shown in the figure is used as a reference, an orthogonal waveform (first orthogonality) at the propagation time t−Δt is assumed. Waveform) and the orthogonal waveform at the propagation time t (second orthogonal waveform) as a set, and the cross correlation processing is executed using these two orthogonal waveforms, thereby obtaining the n1th cross correlation processing result. . Similarly, the orthogonal waveform at the propagation time t (first orthogonal waveform) and the orthogonal waveform at the propagation time t + Δt (second orthogonal waveform) are set as the next set, and cross correlation processing is performed using these two orthogonal waveforms. As a result, an n2th ((n1 + 1) th) cross-correlation processing result is obtained. Here, in the two-dimensional map-like display screen shown in the lower part of FIG. 16, one pixel corresponds to the propagation time Δt, and two orthogonal waveforms between adjacent Δt are taken as one set, and are mutually shifted while being shifted at every Δt. Two orthogonal waveforms to be correlated are specified. As described above, the autocorrelation processing result matches the number of transmissions (transmission number) Np, but the cross-correlation processing result is obtained by a set of two orthogonal waveforms shifted by Δt, that is, by one pixel. Therefore, as described above, the cross-correlation processing result is (Np−1), which is smaller than the number of transmissions (number of transmissions) Np.

  In the two-dimensional map display state shown in the lower part of FIG. 16, if a desired propagation time t is designated by the user with a cursor or pointer, an orthogonal waveform J (first orthogonal waveform) at the propagation time t The cross-correlation processing result using the quadrature waveform J + 1 (second quadrature waveform) at time t + Δt, that is, the n2-th ((n1 + 1) -th) cross-correlation processing result is displayed as shown in the upper diagram of FIG. A pop-up is displayed on the screen of the section 12. The cross-correlation processing result displayed in a pop-up is displayed in a waveform as shown in FIG. 16, with the time difference (τ) on the horizontal axis and the correlation value of the correlation result on the vertical axis. In the two-dimensional map display in the lower diagram in FIG. 16 and the pop-up display in the upper diagram in FIG. 16, the peak position of the correlation value appears on the minus side of the time difference (τ). Thus, by obtaining the cross-correlation processing results (Np−1), the movement direction of the tracer 24 in the container 21 can be detected based on the change in the peak position of the correlation value. Specifically, when the change in the peak position of the correlation value increases to the minus side of the time difference (τ), it indicates that the tracer 24 approaches the ultrasonic sensor 10 side. Conversely, if the change in the peak position of the correlation value increases to the plus side of the time difference (τ), it indicates that the tracer 24 moves away from the ultrasonic sensor 10.

  In FIG. 17, the block diagram of the principal part of the ultrasonic leak detection apparatus 1 'which has the tracer injection | throwing-in apparatus 23 of a present Example is shown. As shown in FIG. 17, the ultrasonic leak detection apparatus 1 ′ of this embodiment includes an ultrasonic sensor 10 having an ultrasonic array sensor 33 </ b> A, an ultrasonic transmission / reception unit 11, a signal processing unit 13, and a transmission / reception condition optimization processing unit 14. The display unit 12 includes a shape display unit 12A, a processing display unit 12B, and a flow rate display unit 12C.

  The ultrasonic array sensor 33 </ b> A includes a plurality of piezoelectric elements, and each piezoelectric element is connected to a connector 11 </ b> F in the ultrasonic transmission / reception unit 11. Then, in accordance with a transmission pulse having a fixed period transmitted from the transmission unit 11A, longitudinal wave ultrasonic waves are transmitted from a piezoelectric element into a medium such as water so that a predetermined transmission time interval ΔTp and a transmission frequency (transmission frequency) Np are obtained. Occurs and propagates through the medium.

  When there is a structure (for example, a pipe 27 (FIG. 9) connected so as to protrude into the container 21) or a reflector such as a tracer 24 such as bubbles or fine particles in the medium, the longitudinal wave ultrasonic wave is The surface of these reflectors reflects mainly as longitudinal wave ultrasonic waves. The ultrasonic wave (reflected wave) reflected by the reflector propagates through the medium and is propagated again to the piezoelectric elements constituting the ultrasonic array sensor 33A. The reflected wave propagated to the piezoelectric element is received as a received wave by the receiving unit 11B via the connector 11F and the switch 11G, converted into digital data, and stored in the storage unit 11D. The received wave converted into digital data and stored in the storage unit 11D is displayed on the display unit 12 as, for example, a received waveform, a two-dimensional cross-sectional image, or a three-dimensional image.

  Here, as the piezoelectric element constituting the ultrasonic array sensor 33A, for example, a piezoelectric ceramic or a composite piezoelectric body (also referred to as a composite) in which a thin rod of the piezoelectric ceramic is embedded in a polymer material is used. The piezoelectric elements are usually arranged at equal intervals.

  The ultrasonic transmission / reception unit 11 of the present embodiment illustrates the case of the delay addition method, and the control unit 11C controls the delay time control unit 11E, and the timing of the transmission pulse (drive signal) output from the transmission unit 11A. And the input timing of the received waveform by the receiving part 12B is controlled. Thereby, the operation of the ultrasonic array sensor 33A by the delay control method is obtained.

  The shape display unit 12A constituting the display unit 12 receives a reception angle of a reflected wave obtained from a reflector such as the structure or the tracer 24 by transmitting ultrasonic waves (in this embodiment, the transmission direction and the reception direction are the same). In this case, a received waveform corresponding to (the transmission angle and the reception angle are the same) is displayed. FIG. 17 shows a fan-shaped display example of digital data of a received waveform when ultrasonic waves are transmitted and received in a range from a start angle to an end angle, with the angle in the circumferential direction and the one-way propagation distance in the axial direction. Note that the method of scanning by changing the transmission angle of ultrasonic waves in this way is called sector scan.

  When the transmission angle is scanned from the start angle to the end angle, the structure in the container 21 in which the ultrasonic array sensor 33A is immersed, for example, a reflected wave from a shape changing portion such as the pipe 27 shown in FIG. The reflected wave from the minute reflector of the tracer 24 such as fine particles is received. Then, as shown in the shape display unit 12A, the entire region 45 of the reflected wave from the shape changing unit and the region 47 of the reflected wave from the tracer 24 in the sector-shaped region correspond to the signal intensity. Displayed as areas of different color or intensity.

  The signal processing unit 13 generates an orthogonal waveform based on the received waveform that is received by the receiving unit 11B and converted into digital data stored in the storage unit 11D. In addition, the signal processing unit 13 performs cross-correlation processing using the generated orthogonal waveform, and displays a correlation image as a cross-correlation processing result on the processing display unit 12B via the control unit 11C. Here, the correlation image displayed on the process display unit 12B is displayed in the display form shown in FIG. For example, the cross-correlation processing result of the orthogonal waveform is displayed on the display unit 12B. One axis is an amount related to transmission time (eg, time difference (τ) of transmission time), and the other axis is an amount related to propagation time (eg, propagation time). The correlation value Rjk (τ) shown in the equation (1) is mapped and displayed. Accordingly, in which time region in the received waveform, the tracer 24 having sufficient conditions (amount, concentration, particle size, etc.) for the flow velocity measurement is put in the container 21, and in which time region the flow velocity It is possible to display whether the measurement result is relatively reliable data. Furthermore, it is also possible to display the change in the flow velocity with respect to the propagation time from the correlation value of the orthogonal waveform on the flow velocity display section 12C.

  In FIG. 17, the case where the signal processing unit 13 executes the orthogonal waveform generation process and the cross-correlation process has been described as an example. However, the present invention is not limited to this. For example, the signal processing unit 13 is the same as in the first embodiment. The orthogonal waveform generation unit 13A and the correlation processing unit 13B may be provided therein, and the orthogonal waveform generation process and the cross-correlation process may be executed respectively.

  Next, leak detection processing by the ultrasonic leak detection apparatus 1 'according to the present embodiment will be described. FIG. 18 is a flowchart of leakage detection processing. In FIG. 18, processing steps similar to those in FIG. 15 shown in the first embodiment are denoted by the same reference numerals, and description thereof is omitted below.

  Steps S10 to S15 are executed in the same manner as the process shown in FIG. 15 described in the first embodiment. The signal processing unit 13 reads the orthogonal waveform generated in step S15 and stored in the storage unit 11D, and calculates cross-correlation processing of the orthogonal waveform (step S20). Here, the cross-correlation processing of the orthogonal waveform is obtained by calculating the normalized correlation coefficient Rjk (τ) in the above equation (1). When compared with the autocorrelation shown in the first embodiment, the moving speed of the tracer 24 can be measured from the vibration (frequency) of the orthogonal waveform, and as a result, the flow rate of the leaked water can be obtained. In addition, it is possible to estimate the direction of the leakage water flow. This is because in the case of autocorrelation processing, the peak of the correlation value always appears where there is no time difference, whereas in the cross-correlation processing, the appearance of the peak of correlation value has a different propagation time as shown in FIG. This is because the degree of phase shift of vibration can be evaluated between two orthogonal waveforms.

  Next, the controller 11C determines whether or not the orthogonal waveform cross-correlation processing by the signal processor 13 has been executed a set number of times in step S20 (step S17). Here, unlike the first embodiment, the set number of times is the number of transmissions (transmission) set by the control unit 11C together with the transmission time interval ΔTp used for generation of transmission pulses to be transmitted from the transmission unit 11A to the ultrasonic sensor 10. Number of times) The number of times obtained by subtracting 1 from Np, that is, (Np-1) times. Therefore, when the number of cross-correlation processing results obtained from the signal processing unit 13 has not reached (Np−1), the control unit 11C returns to step S13 and repeats the processing up to step S17. If the determination result reaches (Np−1), the process proceeds to step S21.

  In step S21, the control unit 11C reads the received waveform, the orthogonal waveform, and the cross-correlation processing result stored in the storage unit 11D, and the shape display unit 12A, the processing display unit 12B, and the flow velocity display unit 12C configuring the display unit 12. Control to display on. As described above, the display on the flow velocity display unit 12C displays the change in the flow velocity with respect to the propagation time from the correlation value obtained by the cross-correlation processing of the orthogonal waveform.

  Subsequent to step S21, in step S19, the control unit 11C obtains the cross-correlation processing result, whether or not there is leakage at the shape changing unit in the container 21 (or the magnitude and direction of the flow velocity with respect to the propagation time of the received waveform, etc. ) And the position of the shape change part are stored in the storage part 11D, and the process returns to step S11. That is, since the leak location is not limited to one location, the process returns to step S11 to search for the next shape change portion in the container 21.

  According to the present embodiment, in addition to the effects of the first embodiment, the movement direction of the tracer 24 can be specified by the cross-correlation processing of the orthogonal waveform, so that it is possible to immediately specify the leak location. Compared with the first embodiment, it is possible to reduce the calculation step for specifying the leaking portion.

  Further, according to the present embodiment, in addition to the effects of the first embodiment, the correlation values obtained by the cross-correlation process are displayed in a two-dimensional map, so that sufficient conditions (quantity, concentration) can be obtained for the flow velocity measurement. It is possible to display whether the tracer 24 of particle size, etc. is put in the container 21 and in which time region the flow velocity measurement result is relatively reliable data. .

  FIG. 19 is a diagram for explaining a highly reliable propagation time region obtained from statistics of correlation results obtained by the ultrasonic leak detection apparatus according to the third embodiment of the present invention. In the second embodiment, the signal processing unit 13 generates a quadrature waveform and performs a cross-correlation process based on the generated quadrature waveform. In the second embodiment, the signal processing unit 13 performs a cross-correlation process of the quadrature waveform. A difference is that the average value and the standard deviation with respect to the propagation time are further obtained with respect to the correlation value obtained as a result of the above. The ultrasonic leak detection device 1 ′ having the tracer input device 23 in the Aimoto embodiment has the configuration shown in FIG. 17 as in the second embodiment.

  As shown in FIG. 19, the signal processing unit 13 calculates statistics such as an average value and a standard deviation with respect to the propagation time for the correlation value obtained by the cross-correlation processing shown in FIG. For example, as shown in the upper diagram of FIG. 19, the horizontal axis represents the propagation time, the vertical axis represents the average correlation value, and the change of the average correlation value obtained as a result of the cross-correlation processing with respect to the propagation time is obtained. Further, as shown in the lower part of FIG. 19, the horizontal axis represents the propagation time, the vertical axis represents the standard deviation of the correlation value, and the change of the standard deviation of the correlation value obtained as a result of the cross-correlation processing with respect to the propagation time is obtained.

  Here, specifically, the signal processing unit 13 calculates the average value of the power spectrum of the correlation value in order to extract the degree of temporal vibration of the correlation value, and further, the standard deviation of the power spectrum of the correlation value Calculate Then, as shown in the upper diagram of FIG. 19, an upper limit threshold value 51A and a lower limit threshold value 51B are set in advance as the threshold value Th1 for the average value. Of the average value of the correlation values with respect to the propagation time, the region a and the region b within the range of the upper threshold 51A and the lower threshold 51B are extracted as the reliable propagation time region 53A and the reliable propagation time region 53B, respectively. The

  Further, as shown in the lower diagram of FIG. 19, a threshold value 52 is set in advance as a threshold value Th2 with respect to the standard deviation. Of the standard deviation with respect to the propagation time, a region c that is equal to or greater than the threshold value 52 is extracted as a highly reliable propagation time region 53C. Then, a region obtained by ANDing these highly reliable propagation time regions 53A, 53B and 53C is extracted as a final highly reliable propagation time region.

  In the example illustrated in FIG. 19, the reliable propagation time region 53 </ b> C is extracted as the final highly reliable propagation time region. The highly reliable propagation time region 53C corresponds to the fact that since the standard deviation is equal to or greater than the threshold value 52, there is little noise component in the vibration of the correlation value, and the flow velocity can be measured with high reliability. Since the average value is within the range of the upper threshold value 51A and the lower threshold value 51B as an absolute value, it can be confirmed that the average value is within the assumed flow velocity range. From this, it is possible to measure the flow rate of the tracer 24 in the container 21, that is, the flow rate of the leaked water with high reliability by the statistics regarding the correlation value, and it is possible to realize the leak detection and the location of the leak with high accuracy. It becomes.

  If the reliable propagation time regions 53A, 53B, and 53C as shown in the upper and lower diagrams of FIG. 19 are not extracted, the transmission / reception condition optimization processing unit 14 shown in FIG. The characteristics of the transmission pulse (transmission pulse transmission time interval ΔTp, transmission frequency (different transmission frequency) Np), impedance of ultrasonic reception, a frequency filter (not shown), and the like are adjusted. This makes it possible to extract a reliable propagation time region, or to optimize transmission / reception conditions so that the time region of the reliable propagation time region becomes longer. Further, as shown in the flow rate display unit 12C in FIG. 17, it is possible to display the flow rate of the tracer 24, that is, the flow rate of leaked water, together with the reliable propagation time region 53D with respect to the propagation time.

  Next, leak detection processing by the ultrasonic leak detection apparatus 1 'according to the present embodiment will be described. FIG. 20 is a flowchart of the leakage detection process. In FIG. 20, processing steps similar to those in FIG. 18 shown in the second embodiment are denoted by the same reference numerals, and description thereof is omitted below.

  Steps S10 to S15 are executed in the same manner as the process shown in FIG. 18 described in the second embodiment. The signal processing unit 13 reads the orthogonal waveform generated in step S15 and stored in the storage unit 11D, and calculates the cross-correlation processing of the orthogonal waveform (step S30). Here, the cross-correlation processing of the orthogonal waveform is obtained by calculating the normalized correlation coefficient Rjk (τ) in the above equation (1). When compared with the autocorrelation shown in the first embodiment, the moving speed of the tracer 24 can be measured from the vibration (frequency) of the orthogonal waveform, and as a result, the flow rate of the leaked water can be obtained. In addition, it is possible to estimate the direction of the leakage water flow. This is because in the case of autocorrelation processing, the peak of the correlation value always appears where there is no time difference, whereas in the cross-correlation processing, the appearance of the peak of correlation value has a different propagation time as shown in FIG. This is because the degree of phase shift of vibration can be evaluated between two orthogonal waveforms.

  Next, the control unit 11C determines whether or not the orthogonal correlation processing of the orthogonal waveform by the signal processing unit 13 has been executed a set number of times in step S30 (step S17). Here, unlike the first embodiment, the set number of times is the number of transmissions (transmission) set by the control unit 11C together with the transmission time interval ΔTp used for generation of transmission pulses to be transmitted from the transmission unit 11A to the ultrasonic sensor 10. Number of times) The number of times obtained by subtracting 1 from Np, that is, (Np-1) times. Therefore, when the number of cross-correlation processing results obtained from the signal processing unit 13 has not reached (Np−1), the control unit 11C returns to step S13 and repeats the processing up to step S17. If the determination result reaches (Np−1), the process proceeds to step S31.

  In step S31, the control unit 11C reads the received waveform, the orthogonal waveform, and the cross-correlation processing result stored in the storage unit 11D, and the shape display unit that configures the display unit 12 illustrated in FIG. Control is performed so as to display on 12A, the process display unit 12B, and the flow velocity display unit 12C. As described above, the display on the flow velocity display unit 12C displays the change in the flow velocity with respect to the propagation time from the correlation value obtained by the cross-correlation processing of the orthogonal waveform. Subsequent to step S31, in step S32, the signal processing unit 13 calculates a statistic such as an average value and a standard deviation with respect to the propagation time with respect to the correlation value obtained by the cross-correlation process, and based on the obtained statistic. Evaluate reliability. Here, reliability evaluation refers to the area obtained by ANDing the high-reliability propagation time regions 53A, 53B, and 53C described in the upper and lower diagrams of FIG. It is executed by extracting as.

  In step S33, the control unit 11C determines whether or not the propagation time region to be measured corresponds to the high reliability region. That is, in step S32, it is determined whether the final reliable propagation region has been extracted or whether the reliable propagation time regions 53A, 53B, and 53C have not been extracted. As a result of the determination, if the reliable propagation time regions 53A, 53B and 53C are not extracted, the process proceeds to step S34. If the final reliable propagation time region is extracted as a result of the determination, the process proceeds to step S19. In the present embodiment, the signal processing unit 13 executes step S32. However, instead of this, step S32 may be executed by the control unit 11C. Moreover, you may comprise so that the signal processing part 13 may perform both step S32 and step S33.

In step S34, the transmission / reception condition optimization processing unit 14 shown in FIG. 17 performs ultrasonic transmission voltage, transmission pulse properties (transmission pulse transmission time interval ΔTp, transmission frequency (difference transmission frequency) Np), and ultrasonic reception. The impedance or a frequency filter (not shown) is adjusted, and the process returns to step S13.
In step S19, the control unit 11C obtains the cross-correlation processing result, whether there is leakage in the shape changing unit in the container 21, or the magnitude and direction of the flow velocity with respect to the propagation time of the received waveform, and the like. The position of the shape change unit is stored in the storage unit 11D, and the process returns to step S11. That is, since the leak location is not limited to one location, the process returns to step S11 to search for the next shape change portion in the container 21.

  According to the present embodiment, in addition to the effects of the second embodiment, the flow rate of the tracer 24 in the container 21, that is, the flow rate of the leaked water can be measured with higher reliability by using the statistical value related to the correlation value. It is possible to specify the location with high accuracy.

  Further, according to the present embodiment, the transmission / reception condition optimization processing unit 14 performs ultrasonic transmission voltage, transmission pulse properties (transmission pulse transmission time interval ΔTp, transmission frequency (different transmission frequency) Np), ultrasonic reception. Since the impedance of the filter or a frequency filter (not shown) is adjusted, the transmission / reception conditions can be optimized so that the reliable propagation time region can be extracted or the time region of the reliable propagation time region becomes longer. .

  In the first to third embodiments described above, the amplitude values of the orthogonal waveforms for each propagation time may be normalized.

  As a noise component (noise component) superimposed on the received waveform, for example, a high-intensity reflected wave from the pipe 27 in the container 21 or the wall surface of the container 21 other than the target tracer 24 or a multiple reflection of these, An electrical noise caused by a moving device 32A having an access jig 22A such as an articulated manipulator or a thruster that holds the acoustic wave sensor 10 and can be moved in water in the container 21, or a place to be a leak detection target is an atom. In an environment under a high dose such as a reactor pressure vessel or a reactor containment vessel, the length of the signal cable connecting the ultrasonic sensor 10 and the receiving unit 11B that receives the signal from the ultrasonic sensor 10 inevitably increases. The signal strength may be attenuated when reaching the receiver. By normalizing the amplitude in each received waveform, that is, in the received waveform corresponding to each transmission time interval ΔTp, when generating an orthogonal waveform (normalization of the amplitude value of the orthogonal waveform for each propagation time) Even in such an environment, it is possible to remove the superimposed noise and extract the reflected wave by the tracer 24 with certainty.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic leak detection apparatus 10 ... Ultrasonic sensor 11 ... Ultrasonic transmission / reception part 11A ... Transmission part 11B ... Reception part 11C ... Control part 11D ... Memory | storage part 11E ... Delay time control part 11F ... Connector 11G ... Switch 12 ... Display Unit 12A ... Shape display unit 12B ... Processing display unit 12C ... Flow rate display unit 13 ... Signal processing unit 13A ... Orthogonal waveform generation unit 13B ... Correlation processing unit 14 ... Transmission / reception condition optimization processing unit 21 ... Container 21A ... Container wall surfaces 22A, 22B ... Jig 23 ... Tracer loading devices 24, 24A, 24B ... Tracer 25 ... Wall hole 26 ... Liquid level 27 ... Pipe 28 ... Double pipe structure 29 ... Tracer moving direction 31 ... Moving device loading openings 32A, 32B ... Moving device 33A ... Ultrasonic array sensor 33B ... Piezoelectric element 41 ... Transmission pulse 42 ... Receiving waveform 43 ... Ultrasonic propagation path 44 ... Receiving waveform 44A ... From shape Reflected wave portion start position 44B ... Amplitude value 45 at propagation time t ... Total reflected wave 45A from shape ... Ultrasonic image boundary 46 ... Sector scan display range 47 ... Reflected wave 51A from tracer ... Upper threshold 51B ... Lower threshold value 52 ... Threshold values 53A, 53B, 53C, 53D ... Reliable propagation time region

Claims (20)

An ultrasonic sensor arranged to be immersed in the liquid in the container;
To the bubble or fine particles or Ranaru tracer is introduced into the liquid in the container, wherein the ultrasonic waves are transmitted by an ultrasonic predetermined outgoing time than the sensor interval and a predetermined number of originations over time of the received waveform to be received A signal processing unit that generates an orthogonal waveform based on an amplitude value of a received waveform corresponding to each of the transmission times in a desired ultrasonic wave propagation time due to a change;
An ultrasonic leak detection apparatus comprising: a display unit configured to display the generated orthogonal waveform or to display the orthogonal waveform and a change with time of the received waveform together. The ultrasonic leak detection device according to claim 1,
The signal processing unit extracts amplitude values at the same ultrasonic propagation time for a plurality of received waveforms corresponding to the number of times of transmission, and arranges the extracted plurality of amplitude values in order of the number of times of transmission. An ultrasonic leak detection device characterized in that The ultrasonic leak detection device according to claim 1,
The signal processing unit delays the ultrasonic wave propagation time at a predetermined equal interval so as to be linear with the number of transmissions for a plurality of received waveforms corresponding to the number of transmissions, and at the equal intervals for each number of transmissions. An ultrasonic leak detection apparatus, comprising: extracting an amplitude value of a received waveform at a delayed ultrasonic wave propagation time; and arranging the extracted plurality of amplitude values in order of the number of transmission times to generate the orthogonal waveform. In the ultrasonic leak detection device according to claim 2 or 3,
The ultrasonic leak detection, wherein the signal processing unit includes a correlation processing unit that performs auto-correlation processing of the generated orthogonal waveform, and removes a noise component included in the received waveform by the auto-correlation processing apparatus. In the ultrasonic leak detection device according to claim 4,
The display unit
The received waveform corresponding to the number of times of transmission is two-dimensionally defined by the number of times of transmission and the ultrasonic wave propagation time, the sampling interval of the received waveform is set as one pixel, and the amplitude value of the received waveform at each sampling time is set to a magnitude. In addition to displaying the map with the corresponding shade value or color,
An ultrasonic leak detection apparatus that pops up an orthogonal waveform corresponding to the designated ultrasonic propagation time when a desired ultrasonic propagation time is designated on the map-displayed screen. In the ultrasonic leak detection device according to claim 2 or 3,
The signal processing unit includes a first orthogonal waveform in the first ultrasonic propagation time among the generated orthogonal waveforms, and a second ultrasonic propagation time different from the first ultrasonic propagation time. An ultrasonic leak detection apparatus comprising a correlation processing unit that performs cross-correlation processing with an orthogonal waveform. The ultrasonic leak detection device according to claim 6,
The correlation processing unit mutually converts two adjacent orthogonal waveforms having different ultrasonic propagation times as the first orthogonal waveform and the second orthogonal waveform among the generated orthogonal waveforms. An ultrasonic leak detection apparatus characterized by performing correlation processing. In the ultrasonic leak detection device according to claim 7,
The display unit
The received waveform corresponding to the number of times of transmission is defined as a two-dimensional sampling interval of the received waveform defined by a time difference that is a difference from each number of times of transmission for each transmission time interval and an ultrasonic propagation time. As a pixel, and a map display with a gray value or color corresponding to the magnitude of the amplitude value of the received waveform at each sampling time,
When a desired ultrasonic propagation time is designated on the map-displayed screen, an orthogonal waveform corresponding to the designated ultrasonic propagation time is set as a first orthogonal waveform, and the designated ultrasonic propagation time is set. And a cross-correlation processing result in which an orthogonal waveform having a different ultrasonic propagation time by the sampling interval of the received waveform is used as a second orthogonal waveform, is pop-up displayed. The ultrasonic leak detection device according to claim 6,
The signal processing unit
An average value and a standard deviation with respect to the ultrasonic propagation time are obtained for the correlation value, which is a cross-correlation processing result obtained by the correlation processing unit, and a preset upper threshold value and lower limit threshold among the obtained average values are obtained. An ultrasonic propagation time region that falls within the value range is extracted as a first reliable propagation time region, and an ultrasonic propagation time region in which the obtained standard deviation is equal to or greater than a preset threshold value is defined as a second reliable propagation time region. An ultrasonic leak detection device characterized by being extracted as a highly reliable propagation time region. The ultrasonic leak detection device according to claim 9,
When neither the first high-reliability propagation time region nor the second high-reliability propagation time region is extracted by the signal processing unit, at least the transmission voltage of the ultrasonic wave transmitted from the ultrasonic sensor and the transmission time An ultrasonic leak detection apparatus comprising a transmission / reception condition optimization processing unit for adjusting any one of an interval and the number of transmissions. In the ultrasonic leak detection device according to claim 2 or 3,
The ultrasonic leak detection apparatus according to claim 1, wherein the signal processing unit normalizes an amplitude value of the generated orthogonal waveform. From ultrasonic sensor is arranged to be immersed in the liquid in the container, wherein the bubble or fine particles or Ranaru tracer is introduced into the liquid in the vessel, the liquid leakage by the received waveform to be obtained by transmitting ultrasonic waves Is a method of detecting
Transmitting ultrasonic waves to the tracer at a predetermined transmission time interval and a predetermined number of transmissions from the ultrasonic sensor;
An orthogonal waveform generating step for generating an orthogonal waveform based on an amplitude value of the received waveform corresponding to each of the number of times of transmission in a desired ultrasonic wave propagation time due to a temporal change of the received waveform obtained by transmitting the ultrasonic wave,
And a display step of displaying the generated orthogonal waveform or the time-dependent change of the orthogonal waveform and the received waveform on a display unit, and a leakage detection method using an ultrasonic leakage detection device. In the leak detection method using the ultrasonic leak detector according to claim 12,
The orthogonal waveform generation step extracts amplitude values in the same ultrasonic propagation time for a plurality of received waveforms corresponding to the number of transmissions, and arranges the extracted amplitude values in order of the number of transmissions. A leakage detection method using an ultrasonic leakage detection device, characterized by generating an orthogonal waveform. In the leak detection method using the ultrasonic leak detector according to claim 12,
The orthogonal waveform generation step delays the ultrasonic wave propagation time at a predetermined equal interval so as to be linear with the number of transmissions for the plurality of received waveforms corresponding to the number of transmissions, and at the same interval for each number of transmissions. The ultrasonic leak detection is characterized in that the amplitude value of the received waveform in the ultrasonic propagation time delayed in this manner is extracted, and an orthogonal waveform is generated by arranging the extracted plurality of amplitude values in order of the number of times of transmission. Leak detection method using a device. In the leak detection method using the ultrasonic leak detection device according to claim 13 or 14,
Leakage detection using an ultrasonic leak detection device comprising a correlation processing step of performing autocorrelation processing of the orthogonal waveform generated by the orthogonal waveform generation step and removing a noise component included in the received waveform Method. In the leak detection method using the ultrasonic leak detector according to claim 15,
The display step includes
The received waveform corresponding to the number of times of transmission is two-dimensionally defined by the number of times of transmission and the ultrasonic wave propagation time, the sampling interval of the received waveform is set as one pixel, and the amplitude value of the received waveform at each sampling time is set to a magnitude. In addition to displaying the map with the corresponding shade value or color,
An ultrasonic leak detection device characterized by popping up an orthogonal waveform corresponding to the designated ultrasonic propagation time when a desired ultrasonic propagation time is designated on the map-displayed screen. The leak detection method used. In the leak detection method using the ultrasonic leak detection device according to claim 13 or 14,
Among the orthogonal waveforms generated by the orthogonal waveform generation step, the first orthogonal waveform at the first ultrasonic propagation time and the second ultrasonic propagation time different from the first ultrasonic propagation time. A leak detection method using an ultrasonic leak detection apparatus, comprising a correlation processing step for performing a cross-correlation process with an orthogonal waveform. In the leak detection method using the ultrasonic leak detector according to claim 17,
In the correlation processing step, among the orthogonal waveforms generated by the orthogonal waveform generation step, two adjacent orthogonal waveforms having different ultrasonic propagation times corresponding to the sampling interval of the received waveform are respectively converted into the first orthogonal waveform and the second orthogonal waveform. A leak detection method using an ultrasonic leak detection apparatus, wherein cross-correlation processing is performed as an orthogonal waveform of the above. In the leak detection method using the ultrasonic leak detector according to claim 17,
An average value and a standard deviation with respect to the ultrasonic wave propagation time are obtained for the correlation value which is a cross-correlation processing result obtained by the correlation processing step, and an upper limit threshold and a lower limit threshold set in advance among the obtained average values. An ultrasonic propagation time region that falls within the value range is extracted as a first reliable propagation time region, and an ultrasonic propagation time region in which the obtained standard deviation is equal to or greater than a preset threshold value is defined as a second reliable propagation time region. A leakage detection method using an ultrasonic leakage detection apparatus, comprising a step of extracting as a highly reliable propagation time region. In the leak detection method using the ultrasonic leak detector according to claim 19,
When neither the first highly reliable propagation time region nor the second highly reliable propagation time region is extracted, at least the transmission voltage of the ultrasonic wave transmitted from the ultrasonic sensor, the transmission time interval, and the number of transmissions A leak detection method using an ultrasonic leak detection device, characterized by comprising a step of adjusting any one of them.

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