Method and apparatus for leak testing pneumatic tube fittings

Abstract

The application relates to the technical field of pneumatic pipe joint leak detection, in particular to a pneumatic pipe joint leak detection method and a leak detection device. The method comprises the following steps: acquiring ultrasonic signals at different positions of a pneumatic pipe joint through a surrounding type ultrasonic detector; matching and positioning multiple leak positions by analyzing the waveform and intensity difference of multiple ultrasonic signals received by different ultrasonic detectors; determining the straight-line distance between each leak source and the ultrasonic detector receiving the ultrasonic signal of each leak source by using the propagation speed and time of the ultrasonic signal; and determining the positions of all leak sources by using the triangulation method. The application aims to improve the accuracy and reliability of leak source detection by identifying and splitting overlapping signals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pneumatic pipe joint leak detection, in particular to a pneumatic pipe joint leak detection method and a leak detection device. BACKGROUND

[0002] A pneumatic pipe joint is a connecting component used in a vehicle pneumatic system, mainly used for connecting air pipes with other pneumatic elements (such as air cylinders, valves, filters, etc.), to ensure smooth gas flow. The pneumatic pipe joint is usually designed to be very simple, easy to install and disassemble, and the side leakage of the pneumatic pipe joint, i.e. the leakage occurring near the interface or contact surface of the pipe joint, usually affects the stability and efficiency of the pneumatic system. The side leakage may be caused by poor sealing, joint aging, improper installation or other factors.

[0003] Currently, whether the pneumatic pipe joint has side leakage is generally detected by ultrasonic detection method. Gas flow generates high-frequency ultrasonic signals near the leakage point, and an ultrasonic detector locates the leakage source by receiving these signals. However, if there are multiple leakage sources at the interface position, and some of the leakage sources are close to each other, the generated ultrasonic signals may overlap, and in complex pipe connection parts, the detection system may not be able to accurately identify each independent leakage source, resulting in false detection. SUMMARY

[0004] To solve the above technical problems, the present application provides a pneumatic pipe joint leak detection method and a leak detection device, and the technical solutions adopted are as follows:

[0005] In a first aspect, one embodiment of the present application provides a pneumatic pipe joint leak detection method, which comprises the following steps:

[0006] An ultrasonic detector of a ring type is arranged to obtain ultrasonic signals at different positions of the pneumatic pipe joint;

[0007] The matching degree of two ultrasonic signals received by any different ultrasonic detectors is determined based on the frequency spectrum centroid difference and the DTW distance between the two ultrasonic signals to determine whether they match, and the matching result is used to determine the ultrasonic signals belonging to the same leakage source from all different ultrasonic detectors;

[0008] The peak width similarity of an ultrasonic signal not belonging to any leakage source is determined based on the width difference between all peaks in the ultrasonic signal, and the superposition confidence of the ultrasonic signal is determined based on the difference between the average power of the ultrasonic signal and the maximum average power of all ultrasonic signals in the ultrasonic detector to which the ultrasonic signal belongs, so as to screen out superposition signals from all received ultrasonic signals;

[0009] determining whether to match according to all unmatched ultrasonic signals received by the ultrasonic detector other than the superposition signal, determining the number of signal sources when the blind source separation method is used to separate signals of the superposition signal according to the logarithm of this matching, and re-matching the matching result after the signal separation of the superposition signal to determine the ultrasonic signals belonging to the same leakage source after the re-matching;

[0010] determining the straight-line distance between each leakage source and the ultrasonic detector receiving the ultrasonic signal to which each leakage source belongs by using the propagation speed and time of the ultrasonic signal, and determining the positions of all the leakage sources by the triangulation method.

[0011] Preferably, the method for determining the matching degree of the two ultrasonic signals is to calculate the normalized value of the product of the difference between the spectrum centers and the DTW distance, and take the difference between the value 1 and the normalized value as the matching degree of the two ultrasonic signals.

[0012] Preferably, the method for determining whether to match by using the matching degree of the two ultrasonic signals is to take the two ultrasonic signals corresponding to the matching degree greater than or equal to the preset matching degree threshold value as the matched ultrasonic signals.

[0013] Preferably, the condition that the ultrasonic signals belonging to the same leakage source are determined from all different ultrasonic detectors according to the matching result is that all the ultrasonic detectors to which the ultrasonic signals belonging to the same leakage source belong one by one correspond to all the set ultrasonic detectors.

[0014] Preferably, the method for determining the peak width similarity is to take the cumulative sum of the width difference between all the peaks in the ultrasonic signal not belonging to any leakage source as the peak width similarity of the ultrasonic signal not belonging to any leakage source.

[0015] Preferably, the method for determining the superposition confidence of the ultrasonic signal is to take the product of the difference between the average power of the ultrasonic signal and the maximum average power in all the ultrasonic signals of the ultrasonic detector to which the ultrasonic signal belongs and the peak width similarity of the ultrasonic signal as the superposition confidence of the ultrasonic signal.

[0016] Preferably, the screening method of the superposition signal is to take the ultrasonic signal corresponding to the superposition confidence greater than or equal to the preset superposition confidence threshold value and the maximum superposition confidence in all the ultrasonic signals received by all the ultrasonic detectors as the superposition signal.

[0017] Preferably, all the ultrasonic signals belonging to the same leakage source after the re-matching respectively belong to each ultrasonic detector one by one corresponding to all the set ultrasonic detectors.

[0018] Preferably, the number of ultrasonic detectors is set to 3.

[0019] In a second aspect, another embodiment of the present application further provides a leak detection device for a pneumatic pipe joint, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the leak detection method for the pneumatic pipe joint according to any one of the above.

[0020] The present application has at least the following beneficial effects:

[0021] The present application optimizes the problem that the ultrasonic signals of multiple leakage sources with similar positions overlap, making the ultrasonic detector unable to accurately identify each independent leakage source. First, the similarity of independent signals is matched through the waveforms of multiple ultrasonic signals of different ultrasonic receiving ends. Then, the overlapping signals and the number of overlapping signal sources are determined according to the signal matching results and signal intensity differences, so as to separate and match the overlapping signals. Finally, the corresponding side leakage positions are determined based on the multiple matched signals of the receiving end through the triangulation method, thereby avoiding the problem that the ultrasonic signals of multiple leakage sources with similar positions at the interface position may overlap, resulting in detection failure of the leakage points, and improving the accuracy and reliability of the leakage source detection. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the drawings needed in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0023] Figure 1 A flowchart of a leak detection method for a pneumatic pipe joint provided by an embodiment of the present application;

[0024] Figure 2 A multi-angle detection schematic diagram of a pneumatic pipe interface cross section provided by an embodiment of the present application;

[0025] Figure 3 A schematic diagram of high-frequency signals received by an ultrasonic detector provided by an embodiment of the present application. DETAILED DESCRIPTION

[0026] An embodiment of the present application provides a leak detection method for a pneumatic pipe joint, which will be specifically described with reference to Figure 1 The method comprises the following steps:

[0027] Step one: Obtain ultrasonic signals at different positions of the pneumatic pipe joint through the set circumferential ultrasonic detector.

[0028] Ultrasonic leak detection technology is a technique that identifies and locates leak sources by detecting ultrasonic signals. This method can detect minute leaks and is particularly suitable for the early detection of gas leaks.

[0029] When gas or liquid leaks from a high-pressure environment to a low-pressure environment, it generates a certain high-frequency sound wave signal due to the collision of airflow and matter. Ultrasonic sensors can capture such high-frequency sound waves and convert the high-frequency ultrasonic signal into an electrical signal to identify the location and intensity of the leak.

[0030] However, vehicles contain complex pipe connections, and multiple leak sources may exist at a single interface location. Using independent ultrasonic detectors, overlapping ultrasonic signals may be generated for leak sources in similar locations. These overlapping signals could prevent the detection system from accurately identifying each individual leak source, leading to misjudgments. Therefore, this embodiment incorporates multi-angle detection of the pneumatic pipe interface cross-section, such as... Figure 2 As shown.

[0031] exist Figure 2 In this design, a surround detection range is formed by three ultrasonic detectors. Each detector emits ultrasonic waves with the same range, ensuring complete coverage of the cylindrical surface corresponding to the pneumatic pipe joint. The distance between each detector and the center of the pneumatic pipe cross-section is the same, while ensuring normal airflow through the pneumatic pipe. Each detector emits sound wave signals of the same frequency and acquires multiple high-frequency signals received by each detector. Each sensor can receive leakage signals from different directions, distinguishing different leakage sources based on differences in signal directionality and intensity. In other embodiments, a surround detection range formed by ultrasonic detectors in multiple directions can be configured according to actual conditions.

[0032] Step 2: Match and locate multiple leakage locations by analyzing the waveform and intensity differences of multiple ultrasonic signals from the receivers of different ultrasonic detectors.

[0033] Since there is superposition of signals from multiple leakage sources, this step first performs similarity matching on the waveforms of multiple ultrasonic signals from different ultrasonic receivers. Then, based on the matching results of the independent signals and the differences in signal strength, the overlapping signals are determined, and the number of signal sources is separated and matched. Finally, based on multiple matching signals from the receivers, the corresponding side leakage location is determined by the triangulation method.

[0034] Therefore, in this embodiment, the specific process of matching the ultrasonic signals and locating possible leakage sources in step two is as follows:

[0035] a. Determine the matching degree of the two ultrasonic signals by using the difference in the centroid of the spectrum and the DTW distance between the two ultrasonic signals received by any different ultrasonic detectors to determine whether they match. Use the matching results to identify ultrasonic signals belonging to the same leakage source from all different ultrasonic detectors.

[0036] Because this embodiment sets up three detection ranges in different directions, and if there are multiple leakage sources at the pneumatic pipe interface, each ultrasonic detector can receive the high-frequency signal generated by each leakage source due to the penetrating power of ultrasonic signals. However, since the distances between different leakage sources and each ultrasonic detector are different, it is impossible to directly determine whether certain high-frequency signals received by each ultrasonic detector belong to the same leakage source. Therefore, this step matches the signals corresponding to different detectors.

[0037] If multiple leak sources exist, the airflow magnitude at different leak sources may vary, resulting in different frequencies and intensities of the corresponding ultrasonic signals. Figure 3 The diagram shows a high-frequency signal received by an ultrasonic detector.

[0038] exist Figure 3 In the diagram, different colored curves represent different high-frequency signals. For a given leakage source, the spectral characteristics and waveform of its generated high-frequency signal will remain consistent after being received by any ultrasonic detector. Therefore, matching needs to be based on this characteristic for segmentation.

[0039] Perform a Fourier Transform (FFT) on each ultrasonic signal from all ultrasonic testing instruments to calculate its spectral centroid. The spectral centroid is used to measure the degree of concentration of a signal across frequencies and is frequently used to distinguish, classify, or describe signal characteristics. The Fourier transform process is a well-known technique and will not be elaborated upon here.

[0040] DTW distance analysis is performed on any two ultrasonic signals from different ultrasonic testing instruments to obtain the corresponding shortest DTW matching distance. The method for DTW distance analysis is a well-known technique and will not be described in detail here.

[0041] Since high-frequency signal waveforms and frequencies belonging to the same leakage source are more similar, the following relationship exists for two ultrasonic signals from any two different ultrasonic detectors: In the formula, For any two ultrasonic signals from different ultrasonic testing instruments and The matching degree, where norm represents the normalization function, is used to... Normalized to the range [0,1] Two ultrasonic signals and DTW shortest matching distance of the two ultrasonic signals, the spectrum centroid of the ultrasonic signal the spectrum centroid of the ultrasonic signal the spectrum centroid of the ultrasonic signal the spectrum centroid of the ultrasonic signal. Wherein, is used to represent the waveform similarity of two ultrasonic signals, the smaller the value, the more similar the waveform, the higher the matching degree. is used to represent the spectrum matching degree of two ultrasonic signals, the smaller the value, the greater the matching degree.

[0042] The result of the matching degree is in the range of [0, 1], and a preset matching degree threshold T is set, which is 0.75 in this embodiment. When , then the corresponding two ultrasonic signals are matching ultrasonic signals, that is, the matching degree between them is high.

[0043] Based on the above method, all ultrasonic signals received by the three ultrasonic detectors in this embodiment are matched, and each matching result is obtained, three corresponding, that is, using the matching result to determine the ultrasonic signals belonging to the same leakage source from all different ultrasonic detectors, which satisfies the condition: all ultrasonic detectors belonging to the ultrasonic signals belonging to the same leakage source are respectively one-to-one corresponding to all set ultrasonic testers. The matched signals are no longer matched to belong to another leakage source, until the remaining ultrasonic signals do not satisfy the matching condition and stop.

[0044] b. According to the width difference between all peaks in the ultrasonic signal not belonging to any leakage source, the peak width similarity of the ultrasonic signal is determined; and combined with the difference between the average power of the ultrasonic signal and the maximum average power in all ultrasonic signals of the ultrasonic detector to which it belongs, the superposition confidence of the ultrasonic signal is determined, so as to screen out the superposition signal from all received ultrasonic signals.

[0045] The above method is used to match the similarity of the ultrasonic signals received by different ultrasonic detectors, but it should be noted that: the premise of matching similar ultrasonic signals together is that both signals are generated by independent same leakage sources, even if received by different ultrasonic detectors, they can still be matched based on their characteristic similarity. But if the distance between some leakage sources and a certain ultrasonic detector is close, the signals generated by these leakage sources can be received almost simultaneously by this ultrasonic detector, and then the signals of these leakage sources will be superimposed together to become a single signal.

[0046] Since the frequency and intensity of multiple superimposed ultrasonic signals differ from those of each individual ultrasonic signal, the matching process described above can only match the non-superimposed signals of independent leakage sources. The unmatched high-frequency signals in the ultrasonic detector may be overlapping signals (or noise signals). Therefore, in order to more accurately locate all leakage sources, this step identifies the possible overlapping signals and performs separation matching.

[0047] The problem of signal superposition occurs when multiple leakage sources are located at similar distances from a certain ultrasonic detector. However, this embodiment uses three ultrasonic detectors to form a three-dimensional surround, so there will be no multiple leakage sources at similar distances from two or more detectors. That is, a superimposed signal will only be received by one ultrasonic detector and will not be matched by the previous step. Here, we first determine the ultrasonic signals that may be superimposed.

[0048] A typical superimposed signal is formed by the fusion of multiple ultrasonic signals, so its signal intensity is higher than that of other ultrasonic signals. At the same time, these signals may have different frequencies, amplitudes, phases, etc. The waveform of the superimposed signal is usually more complex and contains multiple frequency components.

[0049] Therefore, for any ultrasonic detector corresponding to an unmatched ultrasonic signal that does not belong to any leakage source, the worse the frequency consistency and the higher the relative signal strength, the more likely it is to be a superimposed high-frequency signal. The expression for calculating the peak width similarity of ultrasonic signals that do not belong to any leakage source is:

[0050] In the formula, Ultrasonic signals that do not belong to any leakage source Peak width similarity, Ultrasonic signal The number of intermediate peaks and Ultrasonic signal Middle The and the first The width of each peak. Therefore, The similarity between two ultrasonic signals is measured by comparing the difference in the width of any two peaks. The smaller the value, the more similar the peak widths are, and the higher the frequency consistency.

[0051] Therefore, further considering the peak width consistency and relative signal intensity differences of ultrasonic signals, the following relationship exists for an ultrasonic signal that does not belong to any arbitrary leakage source:

[0052] In the formula, Ultrasonic signals that do not belong to any leakage source the superposition confidence of the superposition signal, the average power of the ultrasonic signal, the average power of the ultrasonic signal, the superposition confidence of the superposition signal, the maximum average power of all ultrasonic signals in the ultrasonic detector, the superposition confidence of the superposition signal, the peak width similarity of the superposition signal.

[0053] It should be noted that, the relative intensity of the ultrasonic signal, the greater the value, the stronger the signal intensity of the ultrasonic signal relative to other ultrasonic signals, the more likely it belongs to a superposition signal, and the peak width similarity that is, the greater the value, the more likely the ultrasonic signal is a superposition signal. The result is normalized to the range [0, 1], a preset superposition confidence threshold R is set, and the value of R in this embodiment is 0.88. When , the corresponding ultrasonic signal is a suspected superposition signal, and then the suspected superposition signal that meets the condition is selected for each ultrasonic detector by the above method.

[0054] In addition, if there are suspected superposition signals in multiple ultrasonic detectors, the ultrasonic signal with the maximum value calculated by all ultrasonic detectors is the superposition signal, and the rest are noise signals. If there is no signal that meets the condition in each ultrasonic detector, it means that there is no signal superposition, and the unmatched signal is a noise signal, which excludes the possibility of a leak in the pneumatic connector.

[0055] At this point, the superposition signal in the ultrasonic signal received by different ultrasonic detectors is determined by the above method.

[0056] c. Determine whether the unmatched ultrasonic signal received by the ultrasonic detector other than the superposition signal belongs to the same leakage source according to the number of signal sources when the blind signal source separation method is used to separate the signals of the superposition signal, and match again after signal separation of the superposition signal to determine the ultrasonic signal belonging to the same leakage source after re-matching.

[0057] Since the existence of the superposition signal makes it impossible for the system to accurately locate multiple leakage source positions, it is necessary to separate the superposition signal, and the current blind signal source separation method requires the number of superposition signal sources to be determined in advance when separating signals, as follows:

[0058] Since the existence of the superposition signal makes it impossible for the system to accurately locate multiple leakage source positions, it is necessary to separate the superposition signal, and the current blind signal source separation method requires the number of superposition signal sources to be determined in advance when separating signals, as follows:

[0059] ​If there is a superimposed signal in one of the ultrasonic detectors, due to the complexity of the superimposed signal, there will be a plurality of ultrasonic signals that are not matched in the other two ultrasonic detectors. In this case, the ultrasonic signals that are not matched in the other two ultrasonic detectors are matched in pairs by the method described in step a.

[0060] Since the ultrasonic signals that are not matched in the other two ultrasonic detectors do not have superimposed signals, if they belong to the same leakage source, they will be matched in pairs successfully, and the number of matched signal pairs is obtained .

[0061] It needs to be considered that these signals can be matched in pairs successfully after excluding the ultrasonic detectors corresponding to the superimposed signals, and failed in triple matching in step a. Therefore, the number of matched signal pairs is the number of signal sources of the superimposed signal.

[0062] Based on the number of signal sources of the superimposed signal, the superimposed signal is processed by blind signal source separation method to complete signal separation. Finally, triple matching is performed based on the separated ultrasonic signals by the method in step a. The signals that are not matched successfully are noise signals and can be removed.

[0063] At this point, the ultrasonic signals in different ultrasonic detectors are matched by the above method. That is, three signals that are matched successfully (referred to as a matching group) indicate that they are generated by the same leakage source. Then, the number of matching groups indicates the number of leakage sources at the pneumatic pipe interface. Then, the leakage sources are located.

[0064] Step three: The propagation speed and time of the ultrasonic signal are used to determine the straight-line distance between each leakage source and the ultrasonic detector that receives the ultrasonic signal to which each leakage source belongs. The positions of all the leakage sources are determined by the triangulation method.

[0065] For any matching group, the three ultrasonic signals therein represent the signals generated by the same leakage source when they arrive at different ultrasonic detectors. Since the signals propagate along a straight line, the distances between the leakage source and different detectors are different. Therefore, the arrival time delay of the same signal when it arrives at different detectors is different. The straight-line distance between the signal and each ultrasonic detector can be calculated based on the arrival time delay of the different signals: wherein, is the straight-line distance between the th ultrasonic signal in the matching group and the corresponding leakage source, is the propagation speed of the ultrasonic signal, is the arrival time delay of the The time delay of an ultrasonic signal when it reaches its corresponding ultrasonic detector.

[0066] In this way, the straight-line distance between each leak source and each ultrasonic detector is calculated, and then the corresponding leak source position is accurately located by the three-dimensional triangular positioning method in the three-dimensional space. For each matching group, the calculation is performed to locate all possible leak source positions of the pneumatic pipe interface. The triangular positioning method is a known technology and will not be described again.

[0067] On this basis, the embodiment also models and analyzes multiple leak sources based on the results of multiple scanning detections at different positions:

[0068] Through the above-mentioned way, the leak source position obtained by multi-angle and multi-position scanning for any pneumatic pipe position can use laser scanning or other methods to generate a three-dimensional model of the object. The scanning results at different positions are three-dimensionally reconstructed, which can better present the position, size and influence range of the leak point.

[0069] Through multiple scanning, combined with the data of different sensors, any tiny crack or leak point of the container wall can be accurately captured, thereby improving the accuracy and reliability of leak point detection.

[0070] Another embodiment of the present application also provides a leak detection device for a pneumatic pipe joint, which comprises a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the leak detection method for the pneumatic pipe joint according to any one of the above-mentioned embodiments when executing the computer program.

[0071] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice in the art to which the application pertains.

[0072] It should be understood that the present application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof.

Claims

1. A leak detection method for a pneumatic pipe joint, characterized in that, The method includes the following steps: Ultrasonic signals at different locations of the pneumatic pipe joint were obtained by setting up a surround ultrasonic detector. The matching degree of the two ultrasonic signals is determined by the difference in the centroid of the spectrum and the DTW distance between the two ultrasonic signals received by any different ultrasonic detectors to determine whether they match. The matching result is used to determine the ultrasonic signals belonging to the same leakage source from all different ultrasonic detectors. The peak width similarity of the ultrasonic signal is determined by the width difference between all peaks in the ultrasonic signal that does not belong to any leakage source; and the superposition confidence of the ultrasonic signal is determined by combining the difference between the average power of the ultrasonic signal and the maximum average power of all ultrasonic signals in its ultrasonic detector, so as to filter out the superimposed signal from all received ultrasonic signals. The system determines whether a match is achieved by analyzing all unmatched ultrasonic signals received by the ultrasonic detector other than the superimposed signal. Based on the number of matches, it determines the number of signal sources when using the blind signal source separation method to separate the superimposed signal. After separating the superimposed signal, it is matched again with the result of this match to determine the ultrasonic signals belonging to the same leakage source after the second match. The straight-line distance between each leak source and the ultrasonic tester that receives each ultrasonic signal is determined by using the propagation speed and time of the ultrasonic signal. The location of all leak sources is determined by triangulation.

2. The leak detection method for a pneumatic pipe joint as described in claim 1, characterized in that, The method for determining the matching degree of the two ultrasonic signals is as follows: calculate the normalized value of the product of the difference in the spectral centroids and the DTW distance, and take the difference between the value 1 and the normalized value as the matching degree of the two ultrasonic signals.

3. The leak detection method for a pneumatic pipe joint as described in claim 2, characterized in that, The method for determining whether two ultrasonic signals are matched using their matching degree is as follows: two ultrasonic signals with a matching degree greater than or equal to a preset matching degree threshold are considered as matched ultrasonic signals.

4. The leak detection method for a pneumatic pipe joint as described in claim 3, characterized in that, The method of using matching results to determine ultrasonic signals belonging to the same leakage source from all different ultrasonic detectors satisfies the following condition: all ultrasonic detectors to which ultrasonic signals belonging to the same leakage source belong correspond one-to-one with all the ultrasonic testing instruments that are set up.

5. The leak detection method for a pneumatic pipe joint as described in claim 1, characterized in that, The method for determining the peak width similarity is as follows: the sum of the width differences between all peaks in the ultrasonic signal that does not belong to any leakage source is used as the peak width similarity of the ultrasonic signal that does not belong to any leakage source.

6. The leak detection method for a pneumatic pipe joint as described in claim 1, characterized in that, The method for determining the superposition confidence of the ultrasonic signal is as follows: the product of the difference between the average power of the ultrasonic signal and the maximum average power of all ultrasonic signals in the ultrasonic detector to which it belongs, and the peak width similarity of the ultrasonic signal, is used as the superposition confidence of the ultrasonic signal.

7. The leak detection method for a pneumatic pipe joint as described in claim 1, characterized in that, The method for filtering the superimposed signal is as follows: the ultrasonic signal with a superimposed confidence level greater than or equal to a preset superimposed confidence level threshold, and which is the ultrasonic signal with the highest superimposed confidence level among all ultrasonic signals received by all ultrasonic detectors, is taken as the superimposed signal.

8. The leak detection method for a pneumatic pipe joint as described in claim 1, characterized in that, After rematching, all ultrasonic signals belonging to the same leakage source are associated with each ultrasonic detector, which corresponds one-to-one with all the ultrasonic testing instruments set up.

9. A leak detection method for a pneumatic pipe joint as described in any one of claims 1-8, characterized in that, The number of ultrasonic testing instruments is set to 3.

10. A leak detection device for a pneumatic pipe joint, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements a leak detection method for a pneumatic pipe joint as described in any one of claims 1-9.

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