An air tightness detection system and method

Abstract

The present application relates to air tightness detection technical field, especially in a kind of air tightness detection system and detection method, comprising the following steps: step S1, data are obtained, by setting infrared emission array and the infrared focal plane array corresponding with emission array in detection platform obtain the liquid distribution density inside reservoir;Step S2, density data are analyzed, and the area of bubble generation is locked by the analysis of density data;Step S3, critical value is set, and the starting leakage pressure and the leakage pressure of complete failure of detection component are determined by critical value, by the setting of infrared emission array and infrared focal plane array, the size of bubble quantity when sealing structure failure can be defined by the determined index data, and the damage degree of sealing structure can be defined after weighting, to provide perfect detection data for precision component design.

Description

Technical Field

[0001] This invention relates to the field of airtightness testing technology, and in particular to an airtightness testing system and testing method. Background Technology

[0002] Air tightness testing is a core indicator for many components. It is mainly used to determine the maximum internal pressure that a component can withstand and what changes in internal pressure will cause the sealing structure to fail under normal operating conditions. Most existing air tightness testing methods involve connecting the component to an air source, blocking all other openings, and then immersing it in water to allow air to pass through. When bubbles are generated, it indicates that the sealing structure is damaged. However, this method has a certain lag in manual observation and cannot quantify the entire process of structural damage, making it inconvenient for testing some components with high air tightness requirements. Summary of the Invention

[0003] The purpose of this invention is to provide an airtightness testing system and method to solve the problems existing in the prior art.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: An airtightness detection system, comprising: A water storage tank, wherein a lifting device is fixedly installed at the bottom of the water storage tank, the lifting device being used to move the water storage tank up and down; A testing platform, located above the water storage tank, with its height not adjustable; The data acquisition module is used to acquire detection data.

[0005] By adopting the above technical solution, the component to be tested is fixed at the top center of the testing platform during use. Then, the air source of the testing platform is connected to the air inlet of the component to be tested. Finally, the water tank is raised so that the component to be tested is completely submerged in water. Finally, the data acquisition module acquires the data during the testing process. By analyzing the data, the entire airtightness testing process can be standardized, data-driven, and reconstructed and analyzed.

[0006] This invention also discloses a detection method for an airtightness detection system, comprising the following steps: Step S1: Acquire data by setting up an infrared emitting array and an infrared focal plane array corresponding to the emitting array on the detection platform to obtain the liquid distribution density inside the water storage tank. Step S2: Analyze the density data to pinpoint the area where bubbles are generated. Step S3: Set a critical value to determine the initial leakage pressure and the leakage pressure at which the detection component completely fails.

[0007] By adopting the above technical solution, the water in the reservoir needs to maintain a certain level of cleanliness to avoid excessive consumption of infrared rays emitted by the infrared emitting array in the water. Four vertical plates are evenly arranged around the top of the detection platform. Infrared emitting arrays are fixedly installed on the side of two adjacent vertical plates facing the center of the detection platform. Conversely, infrared focal plane arrays are fixedly installed on the side of the other two adjacent vertical plates facing the center of the detection platform. The infrared emitting array consists of one infrared emitting tube per 4 square centimeters, used to emit infrared beams parallel to the horizontal plane. When the reservoir completely submerges the object to be detected, the water below the surface is relatively... When gas inside the component under test begins to leak, hollow bubbles are generated in the water at the location where bubbles appear. These bubbles deflect infrared light, and the infrared energy passing through the bubbles, sensed by the infrared focal plane array, is weakened. The size of the bubble can be determined by the degree of weakening, the number of bubbles can be determined by the number of attenuated infrared beams, and the density of the bubbles can be determined by the period of energy intensity changes at the receiving end. In this way, the entire process from the onset of leakage in the component under test to the complete failure of the sealing component can be determined. Furthermore, by reverse analysis of the data, it is possible to determine where the sealing structure of the component under test first begins to fail.

[0008] In a further embodiment, step S1 further includes: Data is discarded, and a liquid level gauge is installed inside the water storage tank to calibrate the data acquisition depth. The infrared emitters corresponding to the areas where the infrared focal plane array did not receive energy in the initial state are turned off.

[0009] By adopting the above technical solution, the data acquisition depth needs to be controlled to be 1-2 cm below the water surface inside the reservoir before the test begins. This is to avoid the water surface from sloshing due to the bursting of bubbles after they are generated, which would cause serious data distortion. Therefore, the data acquisition depth needs to be set below the water surface. That is, the water surface must submerge the top end face of the component under test and be at least 30 cm above it. Since the component is completely fixed on the top of the testing platform, the obstruction areas of the component need to be removed to avoid errors caused by the inability to detect data in these areas. After the test begins, the bubbles may deflect infrared light onto the infrared focal plane array in these obstructed areas. If the infrared emitters in these areas are not turned off, it will be impossible to accurately analyze the energy when the infrared focal plane array in these areas senses energy. It will be impossible to determine whether the energy is due to the loss of obstruction after the test object is damaged or the deflection of infrared light by the bubbles. Therefore, the infrared emitters in these obstructed areas need to be turned off.

[0010] In a further embodiment, step S2 further includes: Step S21: Create a corresponding number of three-dimensional line graphs based on the number of infrared emitters used in the detection process. The numbering of the three-dimensional line graphs must be consistent with the numbering of the infrared emitters. Step S22: Determine the position of the infrared beam emitted by the infrared emitter on the infrared focal plane array in the initial state. The origin of each three-dimensional polyline graph is this position. The polylines are marked with colors, and the color represents the energy intensity of the polyline at that position. The Z-axis of the polyline graph represents time with a period of 0.1 seconds. The X-axis and Y-axis of the three-dimensional polyline graph represent the positional relationship between the point where the infrared beam centered at the origin reaches the infrared focal plane array and the origin.

[0011] By adopting the above technical solution, because the infrared emitters are arranged at a high density, in order to avoid interference caused by a large number of bubbles deflecting the infrared rays, the densely packed infrared emitters can be divided into two or more groups. Each group emits at a fixed periodic time interval, and the time nodes of the three-dimensional line graph are aligned with the emission time of the infrared emitters in each group.

[0012] In a further embodiment, the infrared emitting array is divided into four groups of equal number.

[0013] By adopting the above technical solution, the area corresponding to a single infrared emitting tube can be made larger.

[0014] In a further embodiment, the infrared focal plane array is divided into grids according to the number of infrared emitting sources inside the infrared emitting array.

[0015] By adopting the above technical solution, when two energy points are collected at the same time in the same area, the point that is farther from the origin is defined as the point in the area where data is missing.

[0016] In summary, the present invention has the following beneficial effects: 1. By setting up an infrared emitting array and an infrared focal plane array, it is possible to define the amount of air bubbles when the sealing structure fails by using specific index data. After weighting, the degree of damage to the sealing structure can be defined, providing comprehensive detection data for the design of precision components. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram illustrating the positional relationship between the infrared emitting array and the infrared focal plane array of the present invention; Figure 3 This is a schematic diagram illustrating the usage range of the infrared emitting array and infrared focal plane array of the present invention in their working state. Figure 3 The fine cylindrical lines in the image represent the path of the infrared beam emitted by the infrared emitter. Figure 4 This is a three-dimensional polyline diagram illustrating the present invention; Figure 5 This is a schematic diagram used to illustrate the vertical misalignment of two adjacent infrared emitting arrays. Figure 6 This is a schematic diagram of the grouping of infrared emitting tubes inside the infrared emitting array in Embodiments 1 and 2 of the present invention; Figure 7 This is a schematic diagram of the grouping of infrared emitting tubes inside the infrared emitting array in Embodiments 4 and 2 of the present invention.

[0018] In the diagram, 1 is a water storage tank; 2 is a lifting device; 3 is a testing platform; and 4 is a data acquisition module. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] It should be noted that in the description of this invention, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this invention.

[0021] Example 1: like Figure 1 - Figure 6 As shown, an airtightness detection system includes: A water storage tank 1 has a lifting device 2 fixedly installed at its bottom. The lifting device 2 is used to move the water storage tank 1 up and down. Figure 1 As shown, the lifting device 2 is a cylinder, the testing platform 3 is suspended at the top of the inside of the frame, the lifting device 2 is fixedly installed at the bottom of the inside of the frame, and then the water storage tank 1 is fixedly installed on the top of the lifting device 2 to realize the overall lifting of the water storage tank 1; a control cabinet and a compressor need to be installed at the top of the frame. The compressor is used to send high-pressure gas into the inside of the component to be tested through a high-pressure hose, and the control cabinet is used to realize the basic control of the overall function and data acquisition module.

[0022] Testing platform 3 is located above water storage tank 1, and the height of testing platform 3 is not adjustable; Data acquisition module 4 is used to acquire detection data.

[0023] Example 2: like Figure 3 - Figure 6 As shown, it includes the following steps: Step S1: Data Acquisition. The liquid distribution density inside the water tank 1 is acquired by setting up an infrared emitting array and a corresponding infrared focal plane array on the detection platform 3. The acquired data needs to be filtered to avoid excessive computational load and irrelevant data interfering with the data detection logic chain. A liquid level gauge is installed inside the water tank 1 to calibrate the data acquisition depth. The infrared emitters corresponding to areas where the infrared focal plane array did not receive energy in the initial state are turned off. To ensure that every beam of infrared light emitted by the infrared emitting array reaches the corresponding infrared focal plane array, the water in the water tank needs to maintain a certain level of cleanliness to prevent excessive consumption of infrared light emitted by the infrared emitting array in the water. Four vertical plates are evenly arranged around the top of the detection platform. Infrared emitting arrays are fixedly installed on the side of two adjacent vertical plates facing the center of the detection platform. Conversely, the other two adjacent vertical plates... An infrared focal plane array is fixedly installed on the side of the vertical plate facing the center of the testing platform. The infrared emitting array consists of one infrared emitting tube per 4 square centimeters, which is used to emit infrared beams parallel to the horizontal plane. When the water tank completely submerges the object to be tested, the water below the plate is relatively calm. When the gas inside the component to be tested begins to leak, hollow bubbles will be generated in the water at the location where the bubbles appear. The bubbles will deflect the infrared rays, and the infrared energy that passes through the bubbles will be weakened by the infrared focal plane array. The size of the bubble can be determined by the degree of weakening, the number of bubbles can be determined by the number of weakened infrared beams, and the density of the bubbles can be determined by the period of energy intensity change at the receiving end. In this way, the entire process from the beginning of leakage of the component to the complete failure of the sealing component can be known. Furthermore, by reverse analysis of the data, it is possible to determine where the sealing structure of the component to be tested first begins to fail.

[0024] Step S2: Analyze density data to pinpoint the areas where bubbles are generated. First, create a corresponding number of 3D line graphs based on the number of infrared emitters used in the detection process. The line graph numbers must match the infrared emitter numbers. Second, determine the initial position of the infrared beams emitted by the emitters on the infrared focal plane array. The origin of each 3D line graph is this position. Color-code the lines, with each color representing the energy intensity at that position. The Z-axis of the line graph represents time, with a period of 0.1 seconds. The X and Y axes of the 3D line graph represent the positional relationship between the origin point and the point where the infrared beam from the center of the origin reaches the infrared focal plane array. This data acquisition depth needs to be controlled to 1-2 cm below the water surface inside the reservoir before detection begins, to avoid bubbles being trapped in the water after they start generating. The surface cracking causes water to slosh, which severely distorts the test data. Therefore, the data acquisition depth needs to be set below the water surface. Specifically, the water must submerge the top surface of the component under test and be at least 30 centimeters above it. Since the component is completely fixed to the top of the testing platform, any obstructing areas must be removed to prevent errors caused by undetected data in these areas. Furthermore, after testing begins, bubbles may deflect infrared light onto the infrared focal plane array in these obstructed areas. If the infrared emitters in these areas are not turned off, accurate analysis of the energy received by the infrared focal plane array in these areas will be impossible. It will be impossible to determine whether the energy is due to the loss of obstruction after the test object is damaged or due to the deflection of infrared light by bubbles. Therefore, the infrared emitters in these obstructed areas must be turned off.

[0025] Step S3: Set a critical value to determine the initial leakage pressure and the leakage pressure at which the detection component completely fails.

[0026] like Figure 4 As shown, the more red the line color leans, the higher the energy; the more blue the line color leans, the lower the energy.

[0027] Example 3: The grid division method of the infrared focal plane array has been further optimized and limited. The infrared focal plane array is divided into grids according to the number of infrared emitting sources inside the infrared emitting array. The purpose is to solve the problems of cross-interference of energy signals at the receiving end and chaotic data mapping relationship caused by infrared beam deflection in the prior art, thereby improving the spatial resolution and data reconstruction accuracy of the detection system. In practical applications, the infrared emitting array consists of multiple discrete infrared emitting tubes. Each emitting tube occupies a fixed physical position in space and emits an infrared beam at a specific angle. In order to accurately capture the energy change of each infrared beam after passing through the bubble region, the infrared focal plane array at the receiving end must have a matching spatial division capability. Traditional infrared focal plane arrays usually adopt a uniform grid division method, and the number of grids is not directly related to the number of emitting tubes. This leads to the need for additional algorithms to match the correspondence between the emitting source and the receiving unit during signal processing, which increases the computational burden of the system and is also prone to introducing matching errors.

[0028] The grid division method proposed in this invention, based on the number of infrared emitting sources, means that each infrared emitting tube corresponds to an independent and dedicated receiving grid area. During system initialization, all emitting tubes in the infrared emitting array are first numbered, denoted as... ,in and Let represent the row index and column index in the array, respectively. Simultaneously, the detection area of ​​the infrared focal plane array is divided into the same number of grid cells, denoted as . And ensure that the sets of values ​​for m and n are consistent with... , Completely consistent; ideally, when the reservoir contains pure water and no bubbles are generated, the launching tube... The emitted infrared beam travels in a straight line and falls precisely on the corresponding receiving grid. In the central region, the system records the initial energy value received by each grid. This serves as a benchmark for subsequent comparisons.

[0029] During the testing process, when the component under test leaks and generates bubbles, these bubbles cause the infrared light passing through the device to be refracted, scattered, or absorbed, resulting in light that should have reached its destination being filtered out. The energy is partially shifted to adjacent grids until it disappears completely. Since the receiving grids and the transmitting source are in one-to-one correspondence in this embodiment, the system can immediately determine which infrared beam is being interfered with and thus locate the spatial region where the bubble is located. More importantly, when the bubble size is large or the rising speed is fast, a beam of infrared light may be deflected by multiple consecutive bubbles, or the energy of a beam of infrared light may be deflected into multiple different receiving grids. In this case, the grid division method adopted in this embodiment can effectively handle the multi-point reception problem.

[0030] Specifically, this embodiment introduces an algorithm similar to nearest neighbor matching. When the system is in multiple receiving grids within a certain time period... or When energy signals are detected simultaneously at the same locations, the system will first calculate the relative performance of each signal to the original transmitter. The spatial distance to the corresponding ideal receiving position; according to the principle of minimum energy loss in the optical propagation path, the smaller the energy deflection and the closer the receiving grid is to the ideal position, the more likely the signal is that the infrared light emitted directly by the transmitting tube arrives after slight deflection; therefore, the system takes the signal in the grid closest to the ideal receiving point as the main signal and uses its energy change to calculate the size and density of the bubble; while the signals in the grids that are farther away are marked as secondary deflection signals or scattering signals, which are used to help determine the shape and direction of movement of the bubble.

[0031] Furthermore, this embodiment proposes a dynamic grid merging strategy. During the detection process, if the bubble density in a certain area is extremely high, causing the infrared light to be severely deflected or even completely blocked, resulting in the corresponding receiving grid being unable to receive a valid signal for a long time, the system will automatically merge and analyze this grid with its adjacent grids. The merged super grid covers the area corresponding to multiple transmitter tubes and is used to determine whether a large-area sealing structure failure has occurred. This merging operation is not fixed but dynamically adjusted according to real-time data. When the bubble density decreases and the signal is restored, the grid will automatically revert to its original division method.

[0032] By employing the aforementioned grid division method and its accompanying signal processing algorithm, this embodiment significantly enhances the airtightness detection system's ability to detect microbubbles, overlapping bubbles, and high-speed moving bubbles. With an infrared emitter density of one infrared tube per 4 square centimeters, the grid division method of this embodiment enables the system to detect bubbles with a minimum diameter of 0.5 millimeters, measure the bubble rising speed error to less than 5%, and distinguish between two independent bubbles with an adjacent distance of less than 2 millimeters. Compared to the traditional uniform grid division method, this embodiment improves the spatial resolution by approximately 40% and reduces the data matching error rate by more than 65%.

[0033] In summary, this embodiment not only clarifies the grid division method of the infrared focal plane array, but also provides complete data processing logic, enabling the entire detection system to have high-precision and high-robust bubble detection capabilities, providing a solid data foundation for subsequent leak initiation point location, leak intensity assessment, and sealing structure failure process analysis.

[0034] Example 4: like Figure 7 As shown, in this embodiment, the operation of the infrared emitting array has been further optimized. Specifically, the infrared emitting array is divided into four groups of equal numbers. This technical solution is mainly proposed to solve the data distortion problems caused by mutual interference between infrared beams and signal saturation at the receiving end in the prior art. It also helps to improve the time resolution of the system and achieve accurate capture of the rapidly changing dynamic process of bubbles. In a specific implementation, it is assumed that the infrared emitting array contains a total of N infrared emitting tubes, which are arranged in a matrix on two adjacent vertical plates of the detection stage. The distribution is as follows: In order to divide it into four groups, this embodiment first groups them according to the physical location of the transmitting tubes; a preferred grouping method is to divide the entire transmitting array into four sub-regions according to spatial quadrants, with the same number of transmitting tubes in each sub-region, and the transmitting tubes in each sub-region being relatively concentrated in physical location; for example, the transmitting tubes located in the upper left quadrant are the first group, the upper right quadrant is the second group, the lower left quadrant is the third group, and the lower right quadrant is the fourth group; the advantage of this grouping method is that the spatial area covered by the transmitting tubes in the same group is continuous, which facilitates subsequent timing control and region analysis.

[0035] Another preferred division method is staggered grouping, which uses a checkerboard pattern to alternately divide the transmitters into four different groups; for example, the transmitter located at position (i,j) is assigned to the group numbered (i mod 2)×2+(j mod 2)+1. Although this grouping method is slightly more complex to implement, its advantage is that it can minimize the spatial correlation between transmitters within the same group, so that when performing time-division emission, the transmitters lit at any time can be evenly distributed throughout the detection area, avoiding detection blind spots caused by regional signal loss.

[0036] Regardless of the grouping method used, the core of this embodiment is that the four groups of infrared emitting tubes emit infrared beams sequentially according to a preset time order, rather than emitting simultaneously. The specific time control logic is as follows: The system first controls the first group of emitting tubes to emit infrared rays for a duration of Δt. During this period, the infrared focal plane array only collects the energy signal on the receiving grid corresponding to the first group of emitting tubes. Subsequently, the system shuts down the first group and immediately turns on the second group of emitting tubes for the same duration of Δt. The infrared focal plane array then collects the signal corresponding to the second group. This process is repeated until the third and fourth groups have completed their emission and collection, after which the system returns to the first group to begin the next detection cycle. The entire cycle has a period of 4×Δt.

[0037] In this embodiment, the value of Δt needs to be determined based on the rising speed of the bubble and the system's time resolution requirements. After extensive experimental verification, when the bubble diameter is between 0.5 mm and 5 mm and the rising speed is between 0.1 m / s and 0.5 m / s, a value of 0.025 seconds (i.e., 25 milliseconds) is more suitable. At this time, a complete four-cycle period is 0.1 seconds, corresponding to the time period of the Z-axis of the three-dimensional polygonal graph in the original specification. This means that within each 0.1-second time period, the system can complete four complete spatial samplings of the detection area, with each sampling covering one-quarter of the emission tube. By fusing the data from these four samplings, the system can reconstruct the dynamic change process of the bubble within that 0.1-second time period, achieving a time resolution of 25 milliseconds, which is far higher than the 100-millisecond resolution of the traditional simultaneous emission method. Another important improvement brought by this embodiment is the elimination of mutual interference between the transmitters. In the traditional mode where all transmitters operate simultaneously, due to suspended particles in the water, reflection from the surface of bubbles, and multiple scattering effects, a beam of infrared light, after being deflected by bubbles, may enter the receiving grid area that originally belonged to other transmitters, causing false signals. However, in the time-division transmission mode of this embodiment, since only one set of transmitters is working at any given time, while the other three sets are in a closed state, all signals received by the infrared focal plane array at a certain moment can theoretically only come from the currently working set of transmitters. Even if a beam of infrared light is deflected to a distant grid, since other transmitters are not emitting, the signal can still be correctly attributed to a transmitter in the current set, without being confused with signals from other sets.

[0038] Furthermore, this embodiment proposes an adaptive grouping adjustment strategy. During actual detection, the system determines which regions exhibit more intense bubble activity based on the initially collected data. For regions with intense bubble activity, the system can dynamically adjust the launch order and duration of the groups. For example, if a region is found to correspond to the first group of launch tubes, and the bubble density in that region is extremely high, causing drastic signal changes, the system can appropriately shorten the Δt of the other three groups, thereby allocating the saved time to the first group, allowing it to obtain two or even three launch opportunities within one cycle. This asymmetric time-division control method can sample key regions at a higher frequency while keeping the total time period unchanged, thereby obtaining more refined bubble evolution data.

[0039] To verify the technical effectiveness of this embodiment, the inventors conducted a comparative experiment. The experiment used the same component to be tested and the same leakage pressure, employing two modes: simultaneous emission from all transmitting tubes and time-division emission in four groups. The results showed that in the simultaneous emission mode, due to signal interference, the system falsely reported three leakage points at the initial stage of leakage, when there was actually only one. In the time-division emission mode, the system accurately identified the unique leakage point and, through time-series analysis, successfully reconstructed the complete trajectory of the bubble from its generation, rise, and detachment from the component surface. When the leakage was large and the bubbles were dense, the receiver signal in the simultaneous emission mode exhibited saturation, with the energy value of some grids dropping to zero and failing to recover for an extended period, resulting in data loss. In contrast, the time-division emission mode, with only one-quarter of the transmitting tubes operating at a time, had a lower energy density at the receiver and never experienced saturation, ensuring complete recording of all data.

[0040] In summary, this embodiment, by dividing the infrared emitting array into four equal groups and adopting a time-division multiplexing transmission and acquisition mode, not only eliminates signal interference between emitting tubes and improves data quality, but also significantly enhances the system's temporal resolution, making it possible to accurately capture rapid bubble processes. Simultaneously, the introduction of an adaptive grouping adjustment strategy further enhances the system's adaptability to different leakage scenarios. This embodiment is one of the key technologies for achieving high-precision, high-dynamic-range airtightness detection. Simply put, the more groups of infrared emitting tubes inside the infrared emitting array, the larger the usable area of ​​the infrared focal plane array corresponding to each infrared emitting tube, thus solving the problem of interference between infrared rays emitted by adjacent infrared emitting tubes.

[0041] Example 5: Step S3: Set a critical value to determine the initial leakage pressure and the leakage pressure at which the detection component completely fails.

[0042] In the airtightness detection method proposed in this invention, step S3 is the core link of the entire data processing and judgment process; the goal of this step is to, based on the infrared energy attenuation data obtained in step S1 and the three-dimensional polygonal graph analysis results established in step S2, the three-dimensional polygonal graph is as follows: Figure 4 As shown, two key pressure thresholds for the failure of the sealing structure of the component under test are quantitatively defined: the initial leakage pressure. and leakage pressure of complete failure The accurate setting of these two parameters is not only related to the judgment of whether the quality of a single component is qualified, but more importantly, they provide a quantifiable basis for the design optimization of the sealing structure, material selection and process improvement.

[0043] First, the initial leakage pressure To explain, the initial leakage pressure refers to the internal pressure value at which the sealing structure first shows a micro or macro leakage channel and gas begins to escape when the internal pressure of the component under test gradually increases. In the detection method of the present invention, the determination of this moment does not rely on manual observation of bubbles, but is automatically completed by the statistical characteristic changes of the energy signal collected by the infrared focal plane array.

[0044] Specifically, during the testing process, the system continuously pressurizes the inside of the component under test. The pressure rise rate is typically set between 0.01 MPa / s and 0.05 MPa / s, with the specific value determined based on the component's design pressure rating. Simultaneously, the system records the energy attenuation of each infrared emitter-receiver grid channel in real time. ,in Let be the real-time energy received at time t, assuming no leakage. It is caused solely by absorption and scattering by the water itself, and its value is very small and stable, with fluctuations typically not exceeding 2% of the initial energy.

[0045] When the internal pressure reaches a certain critical point and the sealing structure begins to leak slightly, extremely tiny bubbles (with a diameter of less than 0.1 mm) will escape from the leak point. Although these tiny bubbles are difficult to observe with the naked eye, the infrared detection system used in this invention has extremely high sensitivity. When the bubble passes through the infrared beam, even if its diameter is smaller than the spacing between the infrared emitting tubes, it will cause a brief and weak fluctuation in the energy of at least one receiving channel. In order to identify such a weak signal from the noise, this step introduces an algorithm based on statistical hypothesis testing.

[0046] The algorithm first collects energy signals from all channels within the first 30 seconds after the detection begins (it should be noted that the internal pressure is much lower than the expected leakage pressure during this period, so it can be considered as if there is no leakage), and calculates the mean and standard deviation of the energy for each channel. Then, during the subsequent pressurization process, for each channel, the deviation between its current energy value and the initial average value is calculated in real time, and it is determined whether the following conditions are met: Where k is the confidence coefficient, which is 5 in this embodiment; when a certain channel meets the above conditions for 3 consecutive samplings (corresponding to 0.3 seconds), the system determines that a bubble has appeared at the spatial location corresponding to that channel; when the system first detects the above bubble signal in at least one channel, it records the actual pressure value inside the component to be detected at this time and defines it as the initial leakage pressure. To prevent misjudgments caused by accidental disturbances, the system also requires that, within the next 10 seconds after the first detection of a bubble signal, the channel or adjacent channels must still be able to detect a bubble signal for at least 90% of the time; otherwise, it is judged as a false positive, and the system continues to pressurize and search for the initial leak point again.

[0047] It is worth noting that, The determination depends not only on whether a bubble is detected, but also on the spatial location of the bubble; the system automatically records the coordinates of the first receiving grid where a bubble appears. Furthermore, by using a pre-defined spatial mapping relationship, the spatial path of the infrared beam corresponding to the grid on the detection platform can be deduced, thereby determining the two-dimensional plane region where the leak point is located. By using the time difference between the almost simultaneous detection of bubbles by multiple adjacent channels, the escape direction of the bubbles can be further calculated, thereby accurately locking the location of the leak point with an accuracy of ±2 mm.

[0048] Next, the leak pressure of complete failure... The setting is explained; the leakage pressure of complete failure refers to the critical pressure value at which the sealing structure is damaged on a large scale and irreversibly when the internal pressure of the component under test rises to a certain level, resulting in a large amount of gas escaping and the component losing its pressure-holding ability; unlike the initial leakage, complete failure is usually accompanied by a sharp change in the number, size, frequency and spatial distribution range of bubbles.

[0049] In this invention, The determination is based on a comprehensive evaluation of the following four quantitative indicators: Indicator 1: Total Energy Decay Rate , defined as the ratio of the sum of energy attenuation of all effective receiving channels to the initial total energy: ;when When the threshold first exceeds 50% and remains above 5 seconds, it indicates that more than half of the infrared beam has been deflected or absorbed by the bubble, and the leakage is already very serious.

[0050] Indicator 2: Bubble Coverage , defined as the ratio of the number of channels detecting bubbles to the total number of channels at any given time, when When the percentage first exceeds 30%, it indicates that the leak has spread to a large area.

[0051] Indicator 3: Bubble generation frequency By performing a Fourier transform on the energy fluctuations of each channel, the dominant frequency of the bubbles is extracted. When the average bubble frequency of all channels exceeds 20Hz (i.e., 20 bubbles per second), it indicates that the gas escape rate is extremely high.

[0052] Indicator 4: Speed ​​of Spatial Expansion The propagation speed of the bubble signal in the horizontal direction of the detection table is calculated. When the bubble signals between adjacent leak points are connected and the propagation speed exceeds 0.1 m / s, it indicates that the sealing structure has been penetrated.

[0053] During the pressurization process, the system calculates the above four indicators in real time. When any two of the indicators simultaneously reach the above threshold, the system determines that the component under test has reached a complete failure state and records the internal pressure value at this time as the leakage pressure of complete failure. To ensure the robustness of the judgment, the system will also perform a secondary confirmation within 3 seconds after the judgment: if the indicator does not fall back below the threshold within these 3 seconds, then the final confirmation is made. If the indicator falls, the system will continue to apply pressure until the indicator stabilizes and exceeds the threshold.

[0054] In addition to determining and In addition to these two key pressure values, step S3 also includes fitting and analyzing the pressure-leakage intensity curve of the process from initial leakage to complete failure. The system will plot the pressure on the x-axis and the total energy decay rate on the y-axis. Plotting the complete leakage evolution curve with the vertical axis as the ordinate, and then performing piecewise linear fitting on this curve, the rate of change of leakage intensity with pressure can be calculated. The peak of this rate often corresponds to the moment when the sealing structure suffers the most severe damage, and it is an important parameter for evaluating the toughness of sealing materials and structural redundancy.

[0055] In practical applications, and The settings also need to be adjusted according to the specific technical specifications of the component to be tested; for example, for high-pressure gas cylinders used in the aerospace field, the initial leakage pressure must be greater than 1.5 times the maximum working pressure, and the complete failure pressure must be greater than 4 times the maximum working pressure, otherwise it is judged as unqualified; while for ordinary automotive parts, the initial leakage pressure is considered to be qualified if it is greater than 1.2 times the maximum working pressure; the detection system of the present invention allows users to customize these judgment coefficients in the software interface and automatically compare the test results with the standard values ​​to generate a qualified / unqualified report.

[0056] Finally, to facilitate subsequent data traceability and analysis, step S3 will also include all key data generated during the determination process, including the energy-time relationship curve for each channel, the time and location of the first bubble appearance, the curves of the four indicators changing with pressure, and the finally determined... and The data is automatically saved as a structured data file (such as CSV or JSON format) and can be optionally uploaded to the production management system or quality traceability platform. This data can be used not only for quality judgment of individual components, but also for batch statistics to analyze the consistency of sealing performance of products in the same batch, or to compare the process stability between different batches, providing data support for production improvement.

[0057] In summary, step S3, through multi-index and multi-stage algorithm design, achieves accurate, automatic, and repeatable setting of the initial leakage pressure and the complete failure leakage pressure, transforming the subjective judgment that originally relied on human experience into an objective quantitative analysis based on infrared energy attenuation data, greatly improving the scientificity and reliability of airtightness detection.

[0058] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0059] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for detecting air tightness, used to detect air tightness through an air tightness detection system, characterized in that, The airtightness detection system includes: A water storage tank (1) is provided with a lifting device (2) fixedly installed at the bottom of the water storage tank (1). The lifting device (2) is used to move the water storage tank (1) up and down. The testing platform (3) is located above the water storage tank (1), and the height of the testing platform (3) is not adjustable; The data acquisition module (4) is used to acquire detection data. Four vertical plates are evenly arranged on the top circumference of the detection platform (3). Two adjacent vertical plates are fixedly installed with infrared emission arrays on the side facing the center of the detection platform. The other two adjacent vertical plates are fixedly installed with infrared focal plane arrays on the side facing the center of the detection platform (3). The infrared emission array is composed of infrared emission tubes, one per 4 square centimeters, which are used to emit infrared beams parallel to the horizontal plane. When in use, the water level is 30 centimeters higher than the top end face. The airtightness testing method includes the following steps: Step S1: Acquire data by setting up an infrared emitting array and an infrared focal plane array corresponding to the emitting array on the detection platform (3) to obtain the liquid distribution density inside the water storage tank (1), setting up a liquid level scale inside the water storage tank (1), and calibrating the data acquisition depth by setting up the liquid level scale; turn off the infrared emitter corresponding to the area where the infrared focal plane array did not receive energy in the initial state. Step S2: Analyze the density data to pinpoint the area where bubbles are generated. Step S3: Set a critical value to determine the initial leakage pressure and the leakage pressure at which the detection component completely fails.

2. The detection method according to claim 1, characterized in that, Step S1 further includes: The data is discarded, and a liquid level gauge is set inside the water storage tank (1) to calibrate the data acquisition depth. The infrared emitters corresponding to the areas where the infrared focal plane array did not receive energy in the initial state are turned off.

3. The detection method according to claim 1, characterized in that, Step S2 further includes: Step S21: Create a corresponding number of three-dimensional line graphs based on the number of infrared emitters used in the detection process. The numbering of the three-dimensional line graphs must be consistent with the numbering of the infrared emitters. Step S22: Determine the position of the infrared beam emitted by the infrared emitter on the infrared focal plane array in the initial state. The origin of each three-dimensional polyline graph is this position. The polylines are marked with colors, and the color represents the energy intensity of the polyline at that position. The Z-axis of the polyline graph represents time with a period of 0.1 seconds. The X-axis and Y-axis of the three-dimensional polyline graph represent the positional relationship between the point where the infrared beam centered at the origin reaches the infrared focal plane array and the origin.

4. The detection method according to claim 1, characterized in that: The infrared emitting array is divided into four groups of equal number.

5. The detection method according to claim 1, characterized in that: The infrared focal plane array is divided into grids according to the number of infrared emission sources inside the infrared emission array.

Images