JP6450638B2 - Leak detection device - Google Patents

Description

  The present application relates to a leak detection device that detects a detected sound that is an ultrasonic wave generated at a fluid leak point.

  A leak detection device is used to detect a fluid leak point in a piping system or a container of a plant or the like (see, for example, Patent Document 1). The leak detection device can detect the specific position of the fluid leak location by detecting the ultrasonic wave generated at the fluid leak location. Ultrasound is detected using a microphone. The microphone provided in the leak detection device basically detects ultrasonic waves having a predetermined frequency.

JP 2002-323400 A

  In the case of the above-described leak detection device that detects ultrasonic waves of a predetermined frequency, it is difficult to detect ultrasonic waves of other frequencies. Fluids transported through the piping system include vapors, gases such as air and gas, and liquids such as water and liquid agents, and the frequencies of ultrasonic waves generated when these fluids leak are not necessarily the same. Therefore, there is a possibility that ultrasonic waves generated when these fluids leak cannot be detected appropriately only by dealing with a predetermined frequency.

  In this case, a configuration using a microphone that can detect ultrasonic waves in a wide frequency band and a plurality of microphones that detect ultrasonic waves of different frequencies can be considered, but the cost increases.

  An object of the present application is to provide a leak detection device that can detect ultrasonic waves in a wide frequency band while suppressing an increase in cost by using a sound receiving element that detects ultrasonic waves of a predetermined frequency.

  A leak detection device disclosed in the present application for detecting a detected sound that is an ultrasonic wave generated at a fluid leak location includes a sound receiving element, a speaker, and output control means. The sound receiving element detects ultrasonic waves having a detection target frequency. The speaker outputs an added sound having a frequency different from the detection target frequency. The output control means controls the frequency of the added sound output from the speaker within a predetermined range. The output control means controls the frequency of the added sound so that the synthesized sound of the added sound and the detected sound matches the detection target frequency.

  The leakage detection device includes an operation unit that receives an operation input, and a switching control unit that selectively switches between a first mode that does not output the added sound and a second mode that outputs the added sound based on the operation input. And may be further provided.

  The output control means may sweep the frequency of the added sound within the predetermined range as a predetermined time elapses.

  The leak detection device has an inner diameter through which an opening for guiding the detected sound to the inside is formed at one end side, the sound receiving element is disposed inside the other end side, and an ultrasonic wave having the detection target frequency can pass therethrough. A resonance tube may be further provided.

  The speaker may be two speakers having the same polarity, and may be disposed so as to face an inner wall surface on one end side of the resonance tube.

  According to the leak detection apparatus of the present application, the sound receiving element that detects the ultrasonic wave having the detection target frequency is provided, and the added sound having the frequency included in the predetermined range is output from the speaker. Then, the sound receiving element detects the added sound equal to the detection target frequency and the upper synthesized sound or the lower synthesized sound of the detected sound. That is, even if the frequency of the detected sound generated at the fluid leakage location is different from the detection target frequency, it is detected by the sound receiving element when the synthesized sound with the added sound is equal to the detection target frequency. Thereby, it is possible to detect ultrasonic waves in a wide frequency band while suppressing an increase in cost.

1 is an external view of a leak detection apparatus according to Embodiment 1. FIG. 1 is a block diagram of a leak detection apparatus according to Embodiment 1. FIG.

  A leakage detection apparatus according to the present application will be described with reference to the drawings. Note that the configuration of the leak detection apparatus disclosed in the present application is not limited to the following embodiments.

Configuration of First Leakage Detector 1 FIG. 1 is an external view of the leak detector 1. FIG. 2 is a block diagram of the leak detection apparatus 1. The leak detection device 1 is portable and detects a fluid leak location that has occurred in a piping system or a container of a plant or the like. Specifically, by detecting the ultrasonic wave (detected sound) generated at the fluid leakage location with the microphone 11, the fluid leakage location is detected in a non-contact manner. The leak detection apparatus 1 has a first mode for detecting a detected sound equal to the detection target frequency of the microphone 11 and a second mode for detecting a detected sound different from the detection target frequency. Details will be described later.

  The leak detection device 1 includes a main body 10, a microphone 11, speakers 12A and 12B, a signal processing circuit 13, a display unit 14, and an operation unit 15. The main body 10 has a gun shape, and an opening 20 and a resonance tube 21 are disposed at the distal end portion 10A. The opening 20 has a conical shape that tapers in a direction from the external space toward the resonance tube 21, and communicates the external space with the resonance tube 21. The opening 20 guides ultrasonic waves generated in the external space to the resonance tube 21. In the resonance tube 21, two speakers 12 </ b> A and 12 </ b> B are disposed on one end side connected to the opening 20, and the microphone 11 that is a sound receiving element is disposed on the other end side.

  The microphone 11 resonates with sound to be detected having a predetermined frequency (detection target frequency). That is, the microphone 11 detects a detected sound that is equal to the detection target frequency. In this embodiment, 40 KHz is described as the detection target frequency. The detected sound (electric signal) detected by the microphone 11 is input to the signal processing circuit 13. Then, the display unit 14 displays (notifies) that the detected sound has been detected. The resonance tube 21 is formed with an inner diameter that is large enough to allow detection sound equal to the detection target frequency to pass through. That is, the resonance tube 21 has a filter function for removing unnecessary ultrasonic waves.

  The speakers 12 </ b> A and 12 </ b> B have the same polarity and are disposed so as to face the inner wall surface of the resonance tube 21. The speakers 12A and 12B output the same added sound (sine wave) at the same timing in the second mode. Details will be described later.

  The display unit 14 is disposed above the grip G of the main body 10 and displays information such as the detection result of detected sound (presence / absence of detected sound) received from the signal processing circuit 13 (control unit 30). The display unit 14 displays the current execution mode (first mode or second mode). The display unit 14 is a liquid crystal display device, for example.

  The signal processing circuit 13 determines the presence / absence of a detected sound from the electric signal input from the microphone 11 and performs display control of the display unit 14. Moreover, the output of the added sound to the speakers 12A and 12B is controlled. Further, the signal processing circuit 13 switches the execution mode to the first mode or the second mode according to the operation content from the operation unit 15. Details of the configuration of the signal processing circuit 13 will be described later.

  The operation unit 15 (operation means) includes a trigger 16 and the like. The trigger 16 receives an input for mode switching. For example, every time the operator pulls the trigger 16, the first mode and the second mode are alternately switched as the execution mode.

Second First Mode In the first mode, detected sound equal to the detection target frequency (40 KHz) is detected. For example, the operator holds the grip G with one hand and points the distal end portion 10A of the leak detection device 1 toward equipment such as piping to be measured. And the direction of 10 A of front-end | tip parts is changed gradually along the shape of an installation. When the pointing direction of the distal end portion 10A of the leakage detection device 1 is in the vicinity of the fluid leakage location, if the ultrasonic wave (detected sound) radiated from the fluid leakage location is equal to the detection target frequency, the microphone 11 It is detected as a signal and sent to the signal processing circuit 13. Then, the detection result (with detected sound) is displayed on the display unit 14. In the first mode, nothing is output from the speakers 12A and 12B.

Third Second Mode In the second mode, detected sound having a frequency different from the detection target frequency is detected. More specifically, a synthesized sound of the detected sound and the added sound is detected.

During execution of the second mode, the speakers 12A and 12B output the same added sound at the same timing. The added sound is applied to the detected sound that is about to enter the resonance tube 21, and is synthesized (multiplied and synthesized) with the detected sound. The synthesized sound of the added sound and the detected sound includes the upper synthesized sound of the added frequency and the added frequency of the detected sound and the lower synthesized sound of the subtracted frequency.
Addition frequency f = f ₁ + f ₂
Subtraction frequency f = | f ₁ −f ₂ |
(F ₁ : frequency of detected sound, f ₂ : frequency of added sound)

  For example, the synthesized sound of the added sound of 100 KHz and the detected sound of 60 KHz includes an upper synthesized sound of 160 KHz (added frequency) and a lower synthesized sound of 40 KHz (subtracted frequency). In this case, the lower synthesized sound is detected by the microphone 11 because the frequency is 40 KHz, which is equal to the detection target frequency. That is, the leakage detection apparatus 1 (microphone 11) can detect even a detected sound that is different from the detection target frequency by synthesizing with the added sound.

  Further, in this embodiment, a sweep sound that sweeps the frequency in a predetermined range as a predetermined time elapses is output as the added sound. The predetermined range is, for example, 41 KHz to 100 KHz. Therefore, even if the frequency of the detected sound is not specified, if the frequency of the synthesized sound of the addition sound and the detected sound (addition frequency or subtraction frequency) is equal to the detection target frequency, the detection is performed by the microphone 11. Then, the detection result is displayed on the display unit 14 as in the first mode.

  The speakers 12A and 12B are preferably speakers using a piezoelectric ceramic as a vibrator.

Configuration of Fourth Signal Processing Circuit 13 The signal processing circuit 13 includes a control unit 30, a detection circuit unit 40, and an added sound output unit 50. The control unit 30 includes a CPU, a ROM, and the like, and controls the overall operation of the leak detection apparatus 1 based on a program stored in the ROM. Specifically, execution mode switching control, display control on the display unit 14, and output control of added sound are performed. Therefore, the control unit 30 is included in the output control means and the switching control means of the present invention.

  The detection circuit unit 40 includes an amplification unit 41, a filter unit 42, a detection unit 43, a rectification unit 44, an AD converter 45, and the like, and outputs an ultrasonic wave (electric signal) detected by the microphone 11 to the control unit. The ultrasonic wave (electrical signal) detected by the microphone 11 is amplified at a predetermined amplification factor by the amplification unit 41, detected by the detection unit 43 through the filter unit 42, and then rectified by the rectification unit 44. The rectified electrical signal is converted from an analog signal to a digital signal by the AD converter 45 and input to the control unit 30.

  The added sound output unit 50 includes a memory 51, a readout circuit unit 52, a DA converter 53, an amplifying unit 54, and the like, and adds an added sound (sweep sound) based on an instruction (control signal) from the control unit 30 to the speakers 12A and 12B. Output from. The memory 51 is an EEPROM or the like and stores acoustic data of sweep sound. The acoustic data is read from the memory 51 by the readout circuit unit 52 and output to the DA converter 53 as an acoustic signal. Then, the signal is amplified by the amplification unit 54 at a predetermined amplification factor and output from the speakers 12A and 12B as an added sound.

  As described above, in the second mode, the added sound having the frequency within the predetermined range is output from the speakers 12A and 12B, and the added sound equal to the detection target frequency and the upper synthesized sound or the lower synthesized sound of the detected sound are the sound receiving elements. Detected by (microphone 11). That is, even if the frequency of the detected sound generated at the fluid leakage location is different from the detection target frequency, it is detected by the microphone 11 when the synthesized sound with the added sound is equal to the detection target frequency. Thereby, it is possible to detect ultrasonic waves in a wide frequency band while suppressing an increase in cost.

  Further, since the two speakers 12A and 12B are disposed so as to face each other and the added sound is irradiated to the detected sound between the two speakers 12A and 12B, the added sound and the detected sound are easily synthesized. Moreover, since the directions of the speakers 12A and 12B are orthogonal to the direction in which the detected sound enters (the tube direction of the resonant tube 21), the added sound and the detected sound are more easily synthesized. Note that the number of speakers that output the added sound may be one, or may not be orthogonal to the approach direction of the detected sound.

[Other examples]
(1) In the first embodiment described above, the sound pressure level of the added sound is constant, but may be swept within a predetermined level range as a predetermined time elapses. By sweeping in a predetermined level range, the detection accuracy of the synthesized sound by the microphone 11 is increased at the timing when the sound pressure levels of the added sound and the detected sound are equal. In this case, for example, an amplification rate control circuit is provided between the control unit 30 and the amplification unit 54, and the amplification rate control circuit changes the amplification rate of the amplification unit 54 based on an instruction from the control unit 30, so that the sound pressure level Can be controlled.

(2) In the first embodiment described above, the mode is switched, but the mode configuration is not necessary. In this case, for example, a period for outputting the added sound and a period for not outputting the added sound may be set alternately. That is, during the period in which the added sound is output, the detected sound different from the detection target frequency is detected. Then, during the period in which the added sound is not output, the detected sound equal to the detection target frequency is detected.

(3) In the above-described first embodiment, in the second mode, the detected sound different from the detection target frequency is detected by the synthesis with the added sound, but the frequency before the synthesis of the detected sound is further detected. You may make it estimate.

  In this case, the control unit 30 may estimate the frequency of the detected sound before synthesis based on the frequency of the added sound that was output when the microphone 11 detected the synthesized sound. For example, when a 100 KHz added sound and a lower synthesized sound of a detected sound of 60 KHz are detected, the frequency of the added sound is 100 KHz, so the frequency of the detected sound is estimated to be 60 KHz or 140 KHz. The estimated frequency may be displayed on the display unit 14. In addition, the control part 30 should just acquire the information of the frequency of the present addition sound from the addition sound output part 50 (reading circuit part 52).

  Further, the control unit 30 may estimate a more accurate frequency by outputting an additional sound having another frequency based on the estimated frequency. For example, after the frequency of the detected sound is estimated to be 60 KHz or 140 KHz, an additional sound of 20 KHz is output from the speakers 12A and 12B. Thereafter, when the microphone 11 detects the synthesized sound, it can be estimated that the frequency of the detected sound is 60 KHz. When the microphone 11 does not detect the synthesized sound, it can be estimated that the frequency of the detected sound is 140 KHz.

(4) In the above-described first embodiment, the added sound is output in a predetermined range of the frequency of 41 KHz to 100 KHz, but is not particularly limited thereto. For example, the frequency may be 10 KHz to 100 KHz. In this case, the detection target frequency of 40 KHz may be excluded from the predetermined range. That is, 10 KHz to 100 KHz excluding 40 KHz is set as the predetermined range. Or what is necessary is just to make it not detect while making 10 KHz-100 KHz into a predetermined range, and outputting the addition sound of 40 KHz.

(5) The leak detection device of the first embodiment described above is not limited to fluid leaks in pipes and containers, but various fluid leaks in various fields such as fluid leaks in pipe joints, valves such as steam traps and safety valves. Can be used to detect Further, the leaked fluid may be any of vapor, air, gas such as gas, and liquid such as water and liquid agent.

  The present application relates to a leak detection device for detecting a fluid leak location in a piping system or a container of a plant or the like, while suppressing an increase in cost by using a sound receiving element that detects an ultrasonic wave of a predetermined frequency (search target frequency). This is useful for enabling detection of ultrasonic waves in a wide frequency band.

DESCRIPTION OF SYMBOLS 1 Leak detection apparatus 11 Microphone 12A, 12B Speaker 13 Signal processing circuit 21 Resonance tube 30 Control part 40 Detection circuit part 50 Additional sound output part

Claims (5)

A leak detection device for detecting a detected sound that is an ultrasonic wave generated at a fluid leak point,
A sound receiving element for detecting ultrasonic waves of a detection target frequency;
A speaker that outputs an added sound having a frequency different from the detection target frequency;
Output control means for controlling the frequency of the added sound output from the speaker within a predetermined range;
With
The said output control means is a leak detection apparatus which controls the frequency of the said addition sound so that the synthetic sound of the said addition sound and the said to-be-detected sound and the said detection target frequency may correspond. An operation means for receiving an operation input;
The leakage according to claim 1, further comprising switching control means for selectively switching between a first mode in which the added sound is not output and a second mode in which the added sound is output based on the operation input. Detection device.   The leak detection device according to claim 1, wherein the output control unit sweeps the frequency of the added sound within the predetermined range as a predetermined time elapses.   An opening for guiding the detected sound to the inside is formed on one end side, the sound receiving element is disposed inside the other end side, and further includes a resonance tube having an inner diameter through which an ultrasonic wave of the detection target frequency can pass. The leak detection device according to claim 1.   The leak detection device according to claim 4, wherein the speakers are two speakers having the same polarity, and are disposed so as to face an inner wall surface on one end side of the resonance tube.

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