JP7189076B2 - Ultrasonic sensor system - Google Patents

Description

The present invention relates to an ultrasonic sensor system for measuring the thickness of a subject.

For example, in order to measure the thickness of the object being used, it is desired to fix the ultrasonic sensor to the surface of the object, but for some reason it is sometimes difficult to connect the cable between the ultrasonic sensor and the control device. . Patent Literature 1 discloses an ultrasonic sensor system for solving such problems.

The ultrasonic sensor system of Patent Document 1 includes an ultrasonic sensor (ultrasonic transducer) fixed to the surface of the subject and a sensor coil (ultrasonic transducer) fixed to the surface of the subject and connected to the ultrasonic sensor via a cable. transducer coil), a sensor probe having a transmitting coil and a receiving coil capable of transmitting and receiving signals to and from the sensor coil by electromagnetic induction, and a control device connected to the sensor probe via a cable. . This system eliminates the cable between the sensor coil and the sensor probe.

Japanese Patent Application Publication No. 2017-524908 Japanese Patent Application Laid-Open No. 2017-096857 (see FIGS. 10, 11, etc.)

By the way, the method for inspecting the wall thickness of pipes in nuclear power plants in Japan is required to comply with the standards for power generation facilities defined by the Japan Society of Mechanical Engineers. This equipment standard stipulates that a plurality of measurement points be provided in a lattice pattern at intervals of 100 mm or less in the circumferential and axial directions of the pipe, and that the wall thickness be measured using ultrasonic waves at each measurement point. Assuming that the technique described in Patent Document 1 is used to measure the wall thickness of a pipe, the following problems arise.

Each sensor coil in Patent Document 1 has a circular shape and is arranged so as to surround each ultrasonic sensor. Therefore, the plurality of sensor coils, together with the plurality of ultrasonic sensors, must be provided in a grid pattern at intervals of 100 mm or less in the circumferential and axial directions of the pipe. In order to generate electromagnetic induction between the sensor coil and the transmission coil or the reception coil, it is necessary to arrange the transmission coil or the reception coil right above the sensor coil. That is, it is necessary to move the sensor probe in the circumferential direction and the axial direction of the pipe to align it with the sensor coil. Therefore, working time increases.

On the other hand, in the ultrasonic sensor system of Patent Document 2, for example, one sensor coil is connected to a plurality of ultrasonic sensors spaced apart in the circumferential direction of a pipe. This eliminates the need to move the sensor probe in the circumferential direction of the pipe, thereby shortening the working time. However, in the ultrasonic sensor system of Patent Document 2, although the amount of decrease in the thickness of the pipe (maximum value) in the range of the plurality of ultrasonic sensors is measured, the thickness of the pipe at each position of the plurality of ultrasonic sensors is measured. Can not do it.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic sensor capable of measuring the thickness of a subject at each position of a plurality of ultrasonic sensors while shortening the working time. It is to provide a system.

In order to achieve the above object, the present invention provides a plurality of ultrasonic sensors fixed to the surface of a subject and separated from each other, and a plurality of ultrasonic sensors fixed to the surface of the subject and superimposed on each other. a sensor probe having a plurality of sensor coils connected to a sensor in a one-to-one relationship, a transmitting coil and a receiving coil capable of transmitting and receiving signals to and from the plurality of sensor coils by electromagnetic induction; A pulse signal is output to the ultrasonic sensor through the coil and the sensor coil to generate an ultrasonic wave, and the ultrasonic wave reflected by the subject is received by the ultrasonic sensor and converted into a waveform signal by the sensor. In an ultrasonic sensor system comprising a coil and a control device that receives input via the receiving coil, the plurality of ultrasonic sensors have different resonance frequencies, and the control device switches to the resonance frequencies of the plurality of ultrasonic sensors. The frequency of the pulse signal is variably controlled so that the frequency of the pulse signal is changed, and it is identified which of the plurality of ultrasonic sensors the waveform signal corresponding to the pulse signal belongs to, and the plurality of sensor coils are , the number of turns is different so that the impedance with the resonance frequency of the corresponding ultrasonic sensor as a parameter is the same.

According to the present invention, it is possible to measure the thickness of a subject at each position of a plurality of ultrasonic sensors while shortening the working time.

1 is a block diagram showing the configuration of an ultrasonic sensor system according to a first embodiment of the present invention; FIG. FIG. 2 is a diagram showing the arrangement of ultrasonic sensors, sensor coils, transmission coils, and reception coils according to the first embodiment of the present invention; FIG. 4 is a diagram showing characteristics of a plurality of ultrasonic sensors according to the first embodiment of the present invention; FIG. 4 is a block diagram showing the configuration of an ultrasonic sensor system according to a second embodiment of the present invention; FIG. FIG. 10 is a diagram showing the arrangement of ultrasonic sensors, sensor coils, transmission coils, and reception coils according to the second embodiment of the present invention; FIG. 10 is a block diagram showing the configuration of an ultrasonic sensor system in a modified example of the present invention;

A first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an ultrasonic sensor system according to this embodiment. FIG. 2 is a diagram showing the arrangement of ultrasonic sensors, sensor coils, transmission coils, and reception coils in this embodiment. For convenience, FIG. 1 shows the ultrasonic sensors 1A to 1C and 1G, but does not show the ultrasonic sensors 1D to 1F.

The pipe 20, which is the object to be tested in this embodiment, is made of, for example, carbon steel or stainless steel, and becomes hot due to the flow of liquid or gas during operation of the plant. Therefore, it is covered with a heat insulating material 21 made of, for example, calcium silicate, rock wool, glass wool, amorphous kneaded water, or rigid urethane foam.

The ultrasonic sensor system of this embodiment includes a plurality of (seven in this embodiment) ultrasonic sensors 1A to 1G and one sensor coil 2 fixed to the surface (outer surface) of the pipe 20, and the surface of the heat insulating material 21 (outer surface) (in other words, arranged radially outside of the pipe 20 with respect to the ultrasonic sensors 1A to 1G and the sensor coil 2), the sensor probe 5 having the transmission coil 3 and the reception coil 4, and the cable It has a control device 6 connected to the sensor probe 5 via an interface, and a display 7 (display) connected to the control device 6 .

The ultrasonic sensors 1A to 1G correspond to a plurality of measurement points on the pipe 20, respectively, and are spaced apart from each other in the circumferential direction of the pipe 20, for example. Each ultrasonic sensor is composed of, for example, a piezoelectric element, and is made of piezoelectric ceramics such as lead zirconate titanate. The sensor coil 2 is arranged, for example, outside the inspection area of the pipe 20 (in other words, a position different from the ultrasonic sensors 1A to 1G in the axial direction of the pipe 20), and connected to the ultrasonic sensors 1A to 1G via cables. ing. Incidentally, as shown in FIG. 2, a plurality of combinations of the ultrasonic sensors 1A to 1G and the sensor coils 2 may be provided.

The sensor probe 5 can be moved in the axial direction (horizontal direction in FIG. 2) of the pipe 20 by an inspector or a moving device (not shown), and faces the sensor coil 2 . The transmitting coil 3 and the receiving coil 4 of the sensor probe 5 enable transmission and reception of signals by electromagnetic induction between the opposing sensor coils 2 . An electromagnetic wave blocking sheet 8 is provided between the sensor coil 2 and the pipe 20 to prevent electromagnetic induction between the sensor coil 2 and the pipe 20 .

The control device 6 has a signal generator (pulser) 11 , a modulator 12 , a signal receiver (receiver) 13 and a signal processor 14 . The modulator 12 is connected to the transmitter coil 3 of the sensor probe 5 and the signal receiver 13 is connected to the receiver coil 4 of the sensor probe 5 . The signal processor 14 is composed of a processor or the like that executes processing according to a program. Note that the control device 6 further has a memory or the like, stores position information of the ultrasonic sensors 1A to 1G in advance, and stores waveform signals to be described later.

The modulator 12 of the controller 6 variably controls the frequency of the pulse signal generated by the signal generator 11 (details will be described later), and outputs the control information to the signal processor 14 . The transmission coil 3 of the sensor probe 5 converts the pulse signal (electrical signal) from the modulator 12 into a magnetic flux, and the sensor coil 2 converts the magnetic flux into a pulse signal, which is transmitted to the ultrasonic sensors 1A to 1G via cables. output a pulse signal to

The ultrasonic sensors 1A to 1G vibrate by pulse signals from the sensor coil 2 to generate ultrasonic waves. Here, the ultrasonic sensors 1A to 1G have different resonance frequencies. A modulator 12 of the control device 6 variably controls the frequency of the pulse signal so as to sequentially or randomly switch to the resonance frequencies of the ultrasonic sensors 1A to 1G. As a result, the ultrasonic sensors 1A to 1G sequentially or randomly generate ultrasonic waves.

Specifically, the resonance frequency Fa of the ultrasonic sensor 1A, the resonance frequency Fb of the ultrasonic sensor 1B, the resonance frequency Fc of the ultrasonic sensor 1C, the resonance frequency Fd of the ultrasonic sensor 1D, and the resonance frequency Fe of the ultrasonic sensor 1E , the resonance frequency Ff of the ultrasonic sensor 1F and the resonance frequency Fg of the ultrasonic sensor 1G are different. Then, as shown in FIG. 3, when the frequency of the pulse signal is the resonance frequency Fa, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1A increases. Further, as shown in FIG. 3, when the frequency of the pulse signal is the resonance frequency Fb, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1B increases. Further, as shown in FIG. 3, when the frequency of the pulse signal is the resonance frequency Fc, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1C increases. Also, although not shown, when the frequency of the pulse signal is the resonance frequency Fd, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1D increases. Also, although not shown, when the frequency of the pulse signal is the resonance frequency Fe, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1E increases. Further, as shown in FIG. 3, when the frequency of the pulse signal is the resonance frequency Fg, the intensity of the ultrasonic waves generated by the ultrasonic sensor 1G increases. The modulator 12 of the controller 6 variably controls the frequency of the pulse signal so that the resonance frequencies Fa to Fg are switched sequentially or randomly. As a result, the ultrasonic sensors 1A to 1G sequentially or randomly generate ultrasonic waves.

Each ultrasonic sensor transmits ultrasonic waves toward the inner surface of the pipe 20, receives ultrasonic waves reflected on the inner surface of the pipe 20, converts the received ultrasonic waves into a waveform signal (electrical signal), and transmits through the cable A waveform signal is output to the sensor coil 2 . The sensor coil 2 converts the waveform signal from the ultrasonic sensor into a magnetic flux, and the receiving coil 4 of the sensor probe 5 converts the magnetic flux into a waveform signal and outputs the waveform signal to the signal receiver 13 of the control device 6 .

A signal processor 14 of the control device 6 performs predetermined processing on the waveform signal obtained via the signal receiver 13 . Specifically, based on the control information (that is, the frequency of the pulse signal) from the modulator 12, it is identified which of the ultrasonic sensors 1A to 1G the waveform signal corresponding to the pulse signal belongs to. Then, based on the waveform signal of each ultrasonic sensor, the thickness of the pipe 20 at the position of each ultrasonic sensor is calculated, and the calculated thickness of the pipe 20 is used together with the position information or identification information of the corresponding ultrasonic sensor, It is displayed on the display 7. As a method of calculating the thickness of the pipe 20, first, the propagation time of the ultrasonic wave is calculated, for example, with the output timing of the pulse signal as the starting point and the timing at which the amplitude of the waveform signal reaches the maximum as the ending point. Then, the thickness of the pipe 20 is calculated from the propagation time of the ultrasonic wave and the speed of sound.

As described above, in this embodiment, one sensor coil 2 is connected to a plurality of ultrasonic sensors 1A to 1G spaced apart in the circumferential direction of the pipe 20. FIG. Therefore, it is not necessary to move the sensor probe 5 in the circumferential direction of the pipe 20 . Therefore, it is possible to reduce the work load such as movement and alignment of the sensor probe 5 and shorten the work time.

Further, in the present embodiment, the control device 6 switches the ultrasonic sensors that generate ultrasonic waves by variably controlling the frequency of the pulse signal, and the obtained waveform signals are output from the plurality of ultrasonic sensors 1A to 1G. identify which of the This makes it possible to measure the thickness of the pipe 20 at each position of the plurality of ultrasonic sensors 1A-1G.

Also, in this embodiment, the sensor coil 2 is arranged outside the 20 inspection area of the pipe. Therefore, the sensor coil 2 is not restricted in size, unlike the case where it is arranged within the inspection area of the pipe 20 (in other words, between adjacent ultrasonic sensors). As a result, even if the sensor coil 2 and the transmission coil 3 or the reception coil 4 are separated by a large distance due to the interposition of the heat insulating material 21, the outer diameter of the sensor coil 2 is increased so that the sensor coil 2 and the transmission coil 3 or the reception coil 4 are separated. can ensure electromagnetic induction between Therefore, the thickness of the pipe 20 can be measured without attaching and detaching the heat insulating material 21 .

In the first embodiment, the control device 6 calculates the thickness of the pipe 20 at the position of each ultrasonic sensor based on the waveform signal of each ultrasonic sensor, and displays the calculated thickness of the pipe 20 on the display. 7 has been described as an example, but the present invention is not limited to this, and modifications can be made without departing from the gist of the present invention. That is, the control device 6 may cause the display 7 to display the waveform signal of each ultrasonic sensor together with the positional information or identification information of the corresponding ultrasonic sensor. Then, the inspector may calculate the thickness of the pipe 20 at the position of each ultrasonic sensor based on the waveform signal of each ultrasonic sensor displayed on the display 7 .

Further, in the first embodiment, the number of ultrasonic sensors connected to one sensor coil 2 is seven, but the number is not limited to this, and the number may be two or more and six or less. or eight or more. Further, in the first embodiment, a plurality of ultrasonic sensors connected to one sensor coil 2 has been described as an example in which the plurality of ultrasonic sensors are arranged apart from each other in the circumferential direction of the pipe 20. However, the present invention is not limited to this. , may be spaced apart from each other in the axial direction of the pipe 20 , or may be spaced apart from each other in the circumferential direction and the axial direction of the pipe 20 .

A second embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. In addition, in this embodiment, the same code|symbol is attached|subjected to the part equivalent to 1st Embodiment, and description is abbreviate|omitted suitably.

FIG. 4 is a block diagram showing the configuration of the ultrasonic sensor system according to this embodiment. FIG. 5 is a diagram showing the arrangement of ultrasonic sensors, sensor coils, transmission coils, and reception coils in this embodiment. For convenience, FIG. 4 shows the ultrasonic sensors 1A to 1C and 1G and the sensor coils 2A to 2C and 2G, but does not show the ultrasonic sensors 1D to 1F and the sensor coils 2D to 2F.

The ultrasonic sensor system of this embodiment includes a plurality of sensor coils 2A to 2G instead of the sensor coil 2 of the first embodiment. The sensor coils 2A-2G are arranged one above the other and are connected to the ultrasonic sensors 1A-1G via cables in a one-to-one relationship. As described above, in this embodiment, although there are a plurality of sensor coils, since they are concentrated and arranged in one place, the work load such as movement and alignment of the sensor probe 5 is reduced as in the first embodiment. At the same time, working hours can be shortened. Therefore, it is possible to measure the thickness of the pipe 20 at the position of each ultrasonic sensor while shortening the working time.

Further, the sensor coils 2A to 2G of the present embodiment have different numbers of turns so that the impedance is the same with the resonance frequency of the corresponding ultrasonic sensor as a parameter. If the sensor coils 2A to 2G have the same number of turns, the impedance of the sensor coil changes according to the frequency of the pulse signal, and the intensity of the pulse signal and the intensity of the waveform signal change. In this embodiment, due to the features described above, variations in the strength of the waveform signals of the ultrasonic sensors 1A to 1G can be suppressed. Therefore, variations in measurement accuracy of the thickness of the pipe 20 can be suppressed.

In the second embodiment, the number of sensor coils superimposed on each other is described as an example of seven, but the number of sensor coils is not limited to this, and may be two or more and six or less, or eight. There may be more than one. In the second embodiment, the plurality of ultrasonic sensors 1A to 1G connected to the plurality of sensor coils 2A to 2G stacked on each other in a one-to-one relationship are separated from each other in the circumferential direction of the pipe 20. Although the case where they are arranged has been described as an example, they are not limited to this, and may be arranged apart from each other in the axial direction of the pipe 20, or may be arranged apart from each other in the circumferential direction and the axial direction of the pipe 20. good.

Also, in the second embodiment, the case where the number of sensor probes is one has been described as an example, but the present invention is not limited to this, and modifications can be made without departing from the gist of the present invention. That is, the number of sensor probes may be plural. Such a modified example will be described with reference to FIG. In addition, in this modified example, the same code|symbol is attached|subjected to the part equivalent to 1st and 2nd embodiment, and description is abbreviate|omitted suitably.

FIG. 6 is a block diagram showing the configuration of the ultrasonic sensor system in this modified example.

The ultrasonic sensor system of this modification includes a plurality of (two in this embodiment) sensor probes 5A and 5B instead of the sensor probe 5 of the second embodiment. The number of turns of the transmitter coil 3A of the sensor probe 5A and the number of turns of the transmitter coil 3B of the sensor probe 5B are different, and the number of turns of the receiver coil 4A of the sensor probe 5A and the receiver coil 4B of the sensor probe 5B are different.

The sensor probes 5A and 5B are detachable from cables, for example, and configured to be selectively connected to the control device 6. FIG. Then, when the sensor probe 5A is connected to the control device 6, the control device 6 variably controls the frequency of the pulse signal so that, for example, the resonant frequencies of the ultrasonic sensors 1A to 1D are switched sequentially or randomly. Further, when the sensor probe 5B is connected to the control device 6, the control device 6 variably controls the frequency of the pulse signal so as to sequentially or randomly switch to the resonance frequencies of the ultrasonic sensors 1E to 1G, for example.

The sensor coils 2A to 2G of the present embodiment have different numbers of turns so that the impedance is the same using the resonance frequency of the corresponding ultrasonic sensor and the number of turns of the transmission coil and the reception coil of the corresponding sensor probe as parameters. ing. As a result, variations in strength of the waveform signals of the ultrasonic sensors 1A to 1G can be suppressed as in the second embodiment. Therefore, variations in measurement accuracy of the thickness of the pipe 20 can be suppressed.

In the above description, the case where the pipe 20 is covered with the heat insulating material 21 has been described as an example, but the present invention is not limited to this, and the pipe 20 may not be covered with the heat insulating material 21 . Moreover, although the case where the subject is the pipe 20 has been described as an example, the subject is not limited to this, and may be, for example, a container or a flat plate.

1A to 1G Ultrasonic sensors 2, 2A to 2G Sensor coils 3, 3A, 3B Transmitting coils 4, 4A, 4A Receiving coils 5, 5A, 5B Sensor probes 6 Controller 7 Display 20 Piping (subject)

Claims (3)

a plurality of ultrasonic sensors fixed to the surface of the subject and spaced apart from each other ;
a plurality of sensor coils fixed to the surface of the subject, overlapping each other, and connected to the plurality of ultrasonic sensors in a one-to-one relationship;
a sensor probe having a transmitting coil and a receiving coil capable of transmitting and receiving signals to and from the plurality of sensor coils by electromagnetic induction;
A pulse signal is output to the ultrasonic sensor through the transmission coil and the sensor coil to generate an ultrasonic wave, and the ultrasonic wave reflected by the subject is received by the ultrasonic sensor and converted into a waveform signal. In an ultrasonic sensor system comprising the sensor coil and a control device that inputs via the receiving coil,
The plurality of ultrasonic sensors have different resonance frequencies,
The control device variably controls the frequency of the pulse signal so as to switch to resonance frequencies of the plurality of ultrasonic sensors, and the waveform signal corresponding to the pulse signal is selected from any of the plurality of ultrasonic sensors. is identified as
The ultrasonic sensor system according to claim 1, wherein the plurality of sensor coils have different numbers of turns so as to have the same impedance with the resonance frequency of the corresponding ultrasonic sensor as a parameter . In the ultrasonic sensor system according to claim 1 ,
the sensor probes are plural and configured to be selectively connected to the control device, and the number of turns of the transmission coil and the reception coil are different;
The plurality of sensor coils have different numbers of turns so that the impedance is the same with the resonance frequency of the corresponding ultrasonic sensor and the number of turns of the transmitting coil and the receiving coil of the corresponding sensor probe as parameters. An ultrasonic sensor system characterized by: In the ultrasonic sensor system according to claim 1,
The ultrasonic sensor characterized in that the control device displays the waveform signal or the thickness of the subject calculated based thereon on a display together with corresponding positional information or identification information of the ultrasonic sensor. system.

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