Non-contact air tightness testing method combining double differential pressure method with sound source positioning technology

Abstract

The application discloses a kind of non-contact gas tightness test methods of double pressure difference method and sound source positioning technology combination, including gas source system, gas pressure pipeline, pressure vessel cabin, measurement and control system, audio acquisition system and equipment operation platform;Pressure vessel cabin inside is equipped with pressure sensor and audio acquisition system, audio acquisition system is composed of multiple sound sensors, is installed in different directions in pressure vessel cabin;Clean compressed air is provided by gas source system and is passed into fire extinguisher bottle through gas pressure pipeline;The pressure inside fire extinguisher bottle is collected by pressure sensor, and the audio acquisition system collects air leakage sound signal;Measurement and control system combines pressure-time attenuation curve, couples temperature and altitude influence, simulates the change of gas pressure in fire extinguisher bottle;Based on sound wave attenuation algorithm, the air leakage position is fitted according to the sound intensity of different positions.The application avoids the rust problem of traditional bubble method to fire extinguisher bottle, and has high detection precision and high degree of automation.

Description

Technical Field

[0001] This invention belongs to the technical field of fire extinguisher bottle air tightness testing, specifically involving a non-contact air tightness testing method that combines the dual pressure difference method with sound source localization technology. Background Technology

[0002] Before use, fire extinguisher cylinders need to be tested for air tightness to ensure that their air tightness meets the specified requirements.

[0003] Currently, the most widely used methods for airtightness testing are the bubble method and the smear method. The bubble method involves immersing the fire extinguisher in water, injecting compressed air into the bottle, and then visually observing for bubbles to determine if there is a leak and its location. The smear method involves applying a bubble-producing liquid such as soapy water to the surface of the fire extinguisher bottle and observing the bubble formation to detect leaks and their location. While both the bubble method and the smear method are simple to operate, they suffer from drawbacks such as low accuracy, significant susceptibility to human subjective judgment, long testing cycles, and the inability to automate the testing process. Furthermore, due to their inherent testing principles, they are prone to problems such as rusting and corrosion of the fire extinguisher bottle. Summary of the Invention

[0004] The purpose of this invention is to provide a non-contact airtightness testing method that combines the dual differential pressure method with sound source localization technology, in order to solve the corrosion problem existing in the existing fire extinguisher airtightness testing technology, and overcome the problems of large human factors, insufficient detection accuracy, and low efficiency in the existing testing methods.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A non-contact airtightness testing system combining the dual differential pressure method and sound source localization technology includes an air source system, air pressure pipelines, pressure vessel chamber, measurement and control system, audio acquisition system, and equipment operating console; Fire extinguisher cylinders are installed inside the pressure vessel chamber, and the gas supply system is connected to the fire extinguisher cylinders inside the pressure vessel chamber through gas pressure pipelines; the audio acquisition system is installed in the pressure vessel chamber, and the equipment control panel and the audio acquisition system are both connected to the measurement and control system. The air supply system is used to provide clean compressed air and includes an air compressor, filter, desiccant dryer, air tank and pressure relief valve; The pressure vessel chamber is equipped with pressure sensors and the audio acquisition system. The audio acquisition system consists of multiple sound sensors installed in different locations within the pressure vessel chamber. The measurement and control system includes a data acquisition unit and a measurement and control terminal, which consists of an industrial computer and a PLC controller; the measurement and control system adjusts the air compressor speed by controlling the strength of electrical signals. The device control panel is used to digitally display and waveform display the real-time pressure and sound signals of the measurement and control system, and can independently set alarm thresholds; By monitoring the pressure changes inside the fire extinguisher bottle and the pressure vessel chamber during the filling process, the airtightness of the fire extinguisher can be tested. At the same time, the specific location of the leak can be determined by analyzing the sound signals generated when the fire extinguisher bottle leaks.

[0006] Furthermore, the gas generated by the air compressor enters the air storage tank directly through the air pressure pipeline, and the air storage tank is designed with a pressure relief valve; the filter consists of a C-level filter and an A-level filter. The gas output from the air storage tank passes through the C-level filter, the desiccant, and the A-level filter in sequence to separate free oil and water droplets in the air and dry the air. The purified air has an oil content of ≤1ppm, a dust particle size of ≤0.1μm, and a dew point temperature of -70℃.

[0007] Furthermore, the air compressor has a built-in controller with a linkage control mode, uses a PID algorithm, and utilizes vector frequency conversion precision control technology to receive remote control commands via a communication bus; the pressure relief valve is passively controlled; the desiccant requires a power supply for manual power-on setup.

[0008] Furthermore, the acquisition unit includes multiple PLC acquisition channels and a communication module for acquiring voltage signals, current signals, and discrete signals; monitoring the operating status of each part of the non-contact airtightness testing system; and monitoring the parameters that need to be measured for the fire extinguisher bottle under test during the test. The measurement and control terminal is used to control the non-contact airtightness testing system, including an industrial computer and a PLC controller.

[0009] Furthermore, the sound sensor is used to collect the sound of air leakage inside the pressure vessel chamber. Then, through a pre-established analysis model and an algorithm for sound wave attenuation over distance in a confined space, the location of the leak in the fire extinguisher bottle is calculated and fitted based on the sound intensity at different locations. A flow sensor is installed on the gas pressure pipeline to measure the flow rate in the pipeline.

[0010] Furthermore, in the main interface of the system's software testing, the test information area includes real-time curves and test parameters; the real-time curves show how the pressure value changes over time during the test, and these curves are generated and refreshed in real time; in the test parameter interface, the test process can be customized, and the definable test parameters include test stage selection, alarm settings, and leakage calculation parameters; The test process operation area in the main interface of the software test includes alarm, unloading and test start functions; during the test, the real-time curve interface will generate a curve of the pressure change inside the bottle over time, including the pressure rise stage, holding stage, test stage and unloading stage. The automatic monitoring function includes automatic pressurization, pressure stabilization, pressure maintenance, pressure unloading, and real-time pressure monitoring; the fault diagnosis function includes leakage calculation to determine the leakage per unit hour.

[0011] A non-contact airtightness testing method combining the dual-pressure difference method and sound source localization technology includes the following steps: Step 1: Clean compressed air is supplied by the air source system and introduced into the fire extinguisher bottle in the pressure vessel chamber through the air pressure pipeline; Step 2: The pressure sensor inside the pressure vessel chamber collects the internal pressure of the fire extinguisher bottle in real time, and the audio acquisition system collects the sound signal of air leakage inside the pressure vessel chamber. The collected data is transmitted to the measurement and control system. Step 3: The measurement and control system analyzes the pressure signal collected by the pressure vessel chamber, combines the pressure-time decay curve, couples the effects of temperature and altitude, and refers to the pressure changes inside the pressure vessel chamber to simulate and calculate the changes in gas pressure inside the fire extinguisher bottle, which is then displayed on the equipment control panel. Step four: Based on the algorithm of sound wave attenuation over distance in a confined space, the measurement and control system calculates and fits the sound signal collected by the audio acquisition system to determine the location of the leak in the fire extinguisher bottle according to the sound intensity at different locations and through a pre-established analysis model.

[0012] Furthermore, the simulation calculation of the gas pressure change inside the fire extinguisher bottle in step three specifically includes: measuring the internal pressure of the fire extinguisher bottle and the internal pressure of the pressure vessel chamber. When the fire extinguisher bottle leaks, the leaked gas enters the pressure vessel chamber, causing its internal pressure to rise. The leakage amount is calculated by measuring the pressure change inside the pressure vessel chamber before and after the leak.

[0013] Furthermore, the calculation of leakage includes calculating the leakage per unit hour, and the calculation method is as follows: Set the following parameters: Explosion-proof enclosure volume Initial pressure of pressure sensor Pressure sensor pressure at test completion The time when the system starts working and the fire extinguisher cylinder begins to fill. The current time when the test was completed. ; Converted to atmospheric pressure, the calculated leakage rate per unit hour is the gas volume: .

[0014] Furthermore, the pressure-coupled altitude and temperature conversion method uses Matlab data fitting, which can correct environmental parameters for different regions based on historical climate data, and can also correct the simulated target environment by combining the environment of the test site. ; in, For altitude, For temperature, The current air pressure. This is the standard atmospheric pressure at sea level.

[0015] Compared with the prior art, the present invention has the following technical features: 1. The entire testing process requires no manual intervention and is highly automated.

[0016] 2. This invention uses a combination of algorithms for calculation and employs a dual internal and external pressure change testing method. The detection system is more sensitive to pressure changes inside the fire extinguisher tank, and its testing accuracy is higher compared to traditional visual inspection methods.

[0017] 3. The control software of this method allows users to freely set the desired alarm pressure value parameters, making it highly flexible in use.

[0018] 4. This method uses air as the medium to detect leaks in fire extinguisher bottles and uses an acoustic location sensor to locate the leak. The entire testing process does not involve contact with any medium that could contaminate the fire extinguisher bottle, thus avoiding the corrosion problems caused by corrosive media in traditional methods. This greatly reduces the influence of human subjective perception on the test results, while improving detection accuracy and efficiency.

[0019] 5. This method uses air as the medium to detect leaks in fire extinguisher bottles and uses a sound direction recognition sensor to locate the leak. The entire detection process does not come into contact with any medium that could contaminate the fire extinguisher bottle, thus avoiding corrosion problems and locating the leak more accurately and quickly. The influence of human factors in the measurement is greatly reduced.

[0020] 6. This method has strong scalability and can cover other products that need to be tested for similar air tightness with only minimal modifications (only the interface needs to be changed on the hardware side, and the parameters need to be adjusted on the software side).

[0021] 7. The airtightness testing method described in this invention employs integrated multi-parameter real-time dynamic acquisition and intuitive display of dynamic waveforms, enabling the testing of fire extinguisher airtightness under various complex environments. By coupling factors such as temperature and altitude, it provides reference and guidance for subsequent equipment performance assurance, reducing testing costs while possessing significant potential for widespread application. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a non-contact airtightness testing system. Figure 2 This is a schematic diagram of the working principle of the gas source system; Figure 3 This is a schematic diagram of the measurement and control system. Figure 4 This is a schematic diagram of an audio acquisition system.

[0023] Explanation of reference numerals in the attached diagram: 0-Fire extinguisher bottle, 1-Gas supply system, 2-Gas pressure pipeline, 3-Pressure vessel chamber, 4-Measurement and control system, 5-Audio acquisition system, 6-Equipment control panel, 7-Air compressor, 8-Filter, 9-Dryer, 10-Air storage tank, 11-Pressure relief valve, 12-Class C filter, 13-Class A filter, 14-Pressure sensor. Detailed Implementation

[0024] To address the shortcomings of existing technologies, this method innovates by employing a non-contact measurement approach to test the airtightness of fire extinguisher bottles, significantly reducing errors caused by human factors while ensuring non-destructive airtightness testing. By measuring leakage-related parameters such as pressure, pressure difference, and time, a relevant mathematical model is established to analyze and calculate the leakage amount. During the test, an acoustic sensor identifies the sound emitted during gas leakage to pinpoint the exact location. This method is less affected by subjective factors, offers high detection accuracy, and is easily implemented for autonomous detection, automatic control, and automatic alarm, greatly improving detection efficiency while avoiding the corrosion problems caused to fire extinguisher bottles by current bubble methods.

[0025] This invention provides a non-contact airtightness testing method combining the dual-pressure differential method and sound source localization technology. The non-contact airtightness testing system implementing this method includes a gas source system 1, a pressure pipeline 2, a pressure vessel chamber 3, a measurement and control system 4, an audio acquisition system 5, and an equipment operating platform 6. The fire extinguisher bottle 0 is located inside the pressure vessel chamber 3, and the gas source system 1 is connected to the fire extinguisher bottle 0 inside the pressure vessel chamber 3 via the pressure pipeline 2. The audio acquisition system 5 is located in the pressure vessel chamber 3, and both the equipment operating platform 6 and the audio acquisition system 5 are connected to the measurement and control system 4. The principle of this invention is to monitor the pressure changes inside the fire extinguisher bottle 0 and within the pressure vessel chamber 3 during the inflation process to achieve the purpose of airtightness testing of the fire extinguisher bottle 0; simultaneously, the specific leakage location of the fire extinguisher bottle 0 is located by analyzing the collected sound signals generated when the fire extinguisher bottle 0 leaks. This method, for testing the airtightness of fire extinguishers, is based on an algorithm for sound wave attenuation over distance in a confined space and the gas pressure attenuation curve over time in a confined space. It also couples the effects of temperature and altitude, and combines the pressure changes inside the pressure vessel chamber to simulate and calculate the changes in gas pressure inside the fire extinguisher bottle 0, thereby achieving the purpose of verifying the airtightness of the fire extinguisher bottle 0 and the location of leaks.

[0026] Part 1: Gas Source System Setup

[0027] like Figure 1 and Figure 2 As shown, the air supply system 1 provides clean compressed air, which, after filtration, is introduced into the fire extinguisher bottle 0 housed in the pressure vessel chamber 3 via the air pressure pipeline 2. The air supply system 1 includes an air compressor 7, a filter 8, a desiccant 9, an air storage tank 10, and a pressure relief valve 11.

[0028] Air compressor 7 uses electricity to compress air, stably producing an exhaust volume of 15 m³ / min at an absolute pressure of 1.25 MPa. Air compressor 7 has a built-in controller with a linkage control mode, using a PID algorithm and high-performance vector frequency conversion precision control technology. It receives remote control commands via a communication bus to control the operation of air compressor 7. Based on equipment requirements, under the conditions of exhaust pressure ≥15 MPa (absolute pressure) and single-unit outlet flow rate ≥0.5 m³ / min, this embodiment selects the DA-25 type air compressor. To meet the system's demand for higher pressure, a gas booster is used to boost the 0-0.8 MPa compressed gas supplied by the air compressor to 0-15 MPa.

[0029] The gas generated by the air compressor 7 enters the air storage tank 10 directly through the air pressure pipeline 2. The air storage tank 10 serves as a buffer device in the air source system for storing compressed air. A pressure gauge is installed on the tank body to display the real-time gas pressure inside the tank. A pressure relief valve 11 is also installed on the air storage tank 10; the pressure relief valve 11 is passively controlled. In this embodiment, given that the outlet pressure of the system air compressor 7 is 15 MPa, an air storage tank 10 with a rated working pressure > 15 MPa needs to be selected. Considering the system's air consumption, a tank with a volume of 0.5 cubic meters needs to be selected.

[0030] The gas filtration process is completed by filter 8 and desiccant 9. Filter 8 specifically consists of a Class C filter 12 (filtration accuracy 3μm) and a Class A filter 13 (filtration accuracy 0.01μm), forming a three-stage gas filtration system together with the filtration system of the pressure vessel chamber 3 itself. The gas output from the gas storage tank 10 passes through the Class C filter 12, desiccant 9, and Class A filter 13 in sequence, achieving the separation of free oil and water droplets in the air and drying the air. The purified air has an oil content ≤1ppm, a dust particle size ≤0.1μm, and a dew point temperature of -70℃, ensuring the removal of interference factors from the air itself, while also ensuring the cleanliness and integrity of the inside of the fire extinguisher bottle 0.

[0031] When air is compressed, the moisture and oil it contains condense into droplets and mix with dust particles to form acidic sludge, which damages the air pipeline network, air-using equipment, and the final test product. To avoid this, a pipeline filter 8 needs to be added to the air pipeline. The pipeline filter has a compact shape, requiring very little installation space. The filter 8 is equipped with a side view mirror and a differential pressure gauge (or differential pressure indicator), allowing for easy observation of the water level inside the filter through the side view mirror and indicating the replacement time of the filter element through the differential pressure gauge (or differential pressure indicator). The desiccant dryer 9 is responsible for removing free moisture from the air. Due to the high cooling capacity of the cold circuit, it can produce compressed air at a low temperature of -70°C. To avoid condensation during the cooling process, which could cause damage or uncontrollable factors to the air pipeline, air-using equipment, and test control, a dryer is used as the compressed air drying device in the air source system. Based on actual needs, this embodiment selects a micro-heat regenerative adsorption air dryer.

[0032] In the entire air supply system, the air compressor 7 and the desiccant 9 require active control, while the rest are passively controlled. The air compressor 7 has its own controller and a built-in linkage control mode. It can be remotely connected to a PLC to control the operation of the air compressor 7. The desiccant 9 requires a power supply for manual power-on settings before it can operate.

[0033] The equipment control panel 6 can display the real-time pressure and sound signals from the measurement and control system 4 in digital and waveform formats, and can also set alarm thresholds independently.

[0034] Part Two: Construction of the Measurement and Control System.

[0035] like Figure 3 and Figure 4 As shown, the measurement and control system 4 consists of a data acquisition unit, a measurement and control terminal, an equipment operation console 6, and supporting control software.

[0036] The acquisition unit consists of a PLC acquisition channel and a communication module, and has 16 acquisition channels. It can acquire various signals, including voltage signals, current signals, and discrete signals. It is used to monitor the operating status of various parts of the non-contact airtightness testing system (such as air pressure, voltage, and the working status of each module), as well as to monitor the parameters (pressure data, sound data, etc.) that need to be measured in the fire extinguisher bottle under test during the test.

[0037] The measurement and control terminal is used to control the non-contact airtightness testing system. It consists of an industrial computer and a PLC controller. The CPU of the PLC module is a CPU222CN, and the functional modules are: an 8-point digital output module (DO module), a 16-point digital input module (DI module), an 8-channel analog input module (AI module), and an 8-channel analog output module (AO module). All modules are mounted on a standard 480mm long aluminum alloy rail.

[0038] The industrial PC selected is the IPC610 series, equipped with an E7500 processor, 4GB of memory, a 500GB hard drive, a DVD drive, and 12 PCI expansion slots. A 19-inch rack-mount monitor with a resolution of 1920×1080 is used to meet the software's requirements.

[0039] The measurement and control system 4 controls the air compressor 7 by adjusting the strength of the electrical signal, thereby controlling the air source system 1.

[0040] Part Three: Pressure Vessel Chamber and Sensor Arrangement.

[0041] The pressure vessel chamber 3 is used to house the fire extinguisher bottle 0 to be tested. Clean gas supplied by the gas source system 1 is introduced into the fire extinguisher bottle 0 through the pressure vessel chamber 3. The pressure vessel chamber 3 is equipped with a pressure sensor 14 and an audio acquisition system 5. The acquired information is uploaded to the industrial control computer via a PLC module.

[0042] Pressure sensor 14 uses the UNIK5000 series pressure sensor, which is widely used in industrial pressure testing and various aerospace test benches and engine testing fields. The advantages of silicon technology and analog circuits make it have excellent performance in terms of stability, low power and frequency response.

[0043] The audio acquisition system 5 consists of 8 sound sensors installed at the eight corners of the pressure vessel chamber 3. It is used to collect the sound of air leakage inside the pressure vessel chamber 3 and transmit the collected signals to the measurement and control system 4.

[0044] In addition, a flow sensor is installed on the pneumatic pipeline 2 to measure the flow rate in the pipeline, enabling direct and precise measurement of fluid mass flow rate without any conversion or correction for pressure, temperature, viscosity, density, etc.

[0045] The airtightness testing method involves data acquisition via the audio acquisition system 5 inside the pressure vessel chamber 3 and the pressure sensor 14 built into the pressure vessel chamber. The acquired data is analyzed by the measurement and control system 4 and then directly displayed on the equipment control panel 6.

[0046] Part Four: Software Implementation.

[0047] A. Interface design.

[0048] In non-contact airtightness testing software, the operation buttons and test data display during the testing process are displayed on the same interface for easy observation, including the operation area and the test process data display area.

[0049] The test information area in the main interface of the testing software includes real-time curves and test parameters.

[0050] The real-time curve displays how the pressure value changes over time during the test. This curve is generated and refreshed in real time.

[0051] In the test parameters interface, you can customize the test process. There are multiple test processes that can be freely defined. After the definition is completed, you can select the defined test process in the test phase on the right.

[0052] The parameter settings on the right include the following items.

[0053] (1) Selection of testing phase; (2) Alarm settings; (3) Leaking calculation parameters; In the test phase selection, within the test parameter interface mentioned above, you can customize the test process. You can customize multiple processes. Here, select the test process you want to execute at this moment. Clicking the up and down arrows allows you to switch between test processes.

[0054] The alarm settings allow you to set the pressure alarm value inside the fire extinguisher bottle. For example, setting it to 16 MPa means that the device will sound an alarm when the pressure inside the fire extinguisher bottle reaches 16 MPa.

[0055] Leakage calculation parameters include two parameters: fire extinguisher bottle volume and explosion-proof box volume. These two parameters are used to calculate the amount of gas leaking from the bottle.

[0056] B. Testing process.

[0057] The testing process operation area mainly includes three buttons: (1) Alarm; (2) Unloading; (3) Start the test; To activate the alarm, click "Alarm." The buzzer installed in the device will sound an alarm. Clicking here will turn off the alarm sound.

[0058] To unload, click this button. The device will enter the load unloading state. The unloading speed is related to the position of the load switch on the device panel.

[0059] To start the test, click this button. The device will start and execute the selected test procedure.

[0060] During the test, the real-time curve interface will generate a curve showing the change in pressure inside the bottle over time, including the pressure rise phase, the holding phase, the test phase, and the depressurization phase.

[0061] C. Automatic monitoring and fault diagnosis functions.

[0062] C1. Automatic monitoring function.

[0063] Once the test phase is selected, click "Start Test" in the control button area, and the device will begin to automatically execute the test process.

[0064] The automated testing process includes the following tasks: (1) Automatic pressurization is completed; (2) Automatically complete pressure stabilization; (3) Automatically maintain pressure; (4) Automatically complete pressure unloading; (5) Automatically perform real-time pressure monitoring throughout the entire process.

[0065] C2. Fault diagnosis function.

[0066] The test results are displayed in two places within the testing software interface, as follows: (1) Real-time curve: The pressure changes of the fire extinguisher bottle can be seen in the real-time curve graph throughout the entire test process. The pressure change before and after the pressure resistance period can be read from the curve graph. It can be manually calculated and compared with the allowable pressure drop value.

[0067] The test parameters will display the final pressure drop measurement parameters, along with the test process and whether the test data is qualified.

[0068] (2) Leaked calculation results.

[0069] The parameters displayed are as follows: Leakage per unit hour (converted to atmospheric pressure), in L; Leakage per hour, expressed as a percentage; Leakage per unit hour (converted to atmospheric pressure) represents the volume of gas corresponding to the leakage in 1 hour at atmospheric pressure. When this parameter is needed for judgment, it can be used as test data.

[0070] Leakage per unit hour represents the percentage of gas volume corresponding to the leakage within one hour at atmospheric pressure, relative to the gas volume corresponding to the initial pressure inside the bottle at atmospheric pressure. This parameter can be used as experimental data when needed for judgment.

[0071] Part 5: Logical Analysis Model and Detection Methods.

[0072] The detection principle of this method combines the dual-pressure difference method with sound source localization technology. By collecting the internal pressure and sound signals of the fire extinguisher bottle 0 under test, and considering the pressure changes within the pressure vessel chamber 3, the system checks whether the fire extinguisher bottle 0 has an airtightness problem. The measurement and control system 4 analyzes the pressure signals collected from the pressure vessel chamber 3, combines the pressure-time decay curve, couples the effects of temperature and altitude, and references the internal pressure changes within the pressure vessel chamber 3 to simulate and calculate the internal gas pressure changes of the fire extinguisher bottle 0. This calculation is displayed in real time on a monitor, thus achieving the purpose of detecting the airtightness of the fire extinguisher bottle.

[0073] (1) Select “Non-contact airtightness testing technology research software” through the computer monitor interface; (2) In the “Design Parameters” table, you can enter parameters such as “Test Pressure”, “Pressure Holding Time”, “Permissible Pressure Drop”, and “Pressure Increase Rate”; (3) Click the “vent” button to vent the test fire extinguisher bottle.

[0074] (4) The venting process can be repeated several times to ensure that the test specimen is completely vented. Incomplete venting or forgetting to vent will lead to poor test results and the test process will be very dangerous. Therefore, venting must be done before the formal test; after venting is completed, turn off the venting switch.

[0075] (5) Click the “Start Test” button to start the test; the pump starts working, and you can adjust the pressure increase rate to adjust the pressure increase speed. It will automatically stop when the set pressure is reached. It will automatically unload when the pressure holding time is reached.

[0076] I. Leakage Calculation.

[0077] Set the following parameters: Fire extinguisher bottle volume (Unit: L), in this embodiment L; Explosion-proof container volume (i.e., the volume of the pressure vessel compartment 3 excluding the space occupied by fire extinguishers). (Unit: L), a fixed constant value; the internal pressure of the fire extinguisher bottle is 0 when the pressure test is completed. (Unit: Pa); Initial pressure of the pressure sensor (Unit: Pa); Pressure sensor pressure at the end of the test (Unit: Pa); Time of system startup and fire extinguisher cylinder starting to fill. (Unit: min); Current time when the test was completed. (Unit: min); Fire extinguisher bottle pressurization time (Unit: min)

[0078] The leakage rate per unit hour (converted to atmospheric pressure) is calculated to determine the gas volume. ; Leakage per unit hour (percentage), calculated as a percentage of the cylinder's contents: .

[0079] II. Sound source localization.

[0080] The monitoring and control system 4 uses an algorithm based on the attenuation of sound waves over distance in a confined space. Based on the sound intensity at different locations, it calculates and fits the sound signals collected by the audio acquisition system 5 to determine the leak location of the fire extinguisher bottle 0. Specifically, multiple sound sensors are installed at different locations within the pressure vessel chamber 3 to identify the faint sound emitted by a gas leak, thereby accurately locating the angle of the sound source. Then, through a pre-established analysis model, the precise location of the gas leak is calculated. This analysis model is based on using the spatial coordinates of each sound sensor as known quantities and the sound intensity values ​​collected by each sensor as input quantities. By solving the sound wave attenuation equation, the three-dimensional spatial coordinates of the leak sound source within the pressure vessel chamber 3 are calculated in reverse, thus determining the precise location of the leak hole on the fire extinguisher bottle 0.

[0081] III. Pressure coupling altitude and temperature conversion.

[0082] Considering that this method focuses on airtightness, the effect of different altitudes and temperatures on the airtightness of fire extinguisher cylinders is simulated by creating a pressure difference between the inside and outside of the cylinder to equivalently test the effect of different altitudes. Specifically, this is achieved by increasing the internal pressure of the pressure vessel chamber 3 while simultaneously decreasing the internal pressure of the fire extinguisher cylinder 0. The effect of temperature can be assessed by changing the temperature of the gas filling the fire extinguisher cylinder 0 to achieve equivalent airtightness testing under different temperature differences.

[0083] The pressure-coupled altitude and temperature conversion method uses Matlab data fitting. This method can correct environmental parameters for different regions based on historical climate data, and can also correct the simulated target environment based on the environment of the test site, so as to achieve the goal of simulating the equipment's operating conditions to the greatest extent. ; in, Elevation (unit: m) Temperature (unit: °C) The current air pressure. The standard atmospheric pressure is at sea level. When it is necessary to simulate the airtightness of fire extinguisher bottles under different altitudes and temperatures, the atmospheric pressure of the target environment is first calculated using a formula, and then the pressure value inside pressure vessel chamber 3 is set accordingly (i.e., the pressure inside the chamber is increased or decreased) to create equivalent pressure difference conditions.

[0084] Compared with existing technologies, this invention has the following advantages: The entire testing process requires no manual contact, resulting in a high degree of automation; it employs a dual internal and external pressure change testing model, coupled with multiple algorithms for calculation, making the detection system more sensitive to internal pressure changes in fire extinguisher bottles and achieving higher testing accuracy compared to traditional visual inspection methods; the control software allows for flexible setting of desired alarm pressure parameters; the testing process uses air as the medium to detect leaks in the fire extinguisher bottle, and a sound sensor to locate the leak. The entire testing process avoids contact with any media that could contaminate the fire extinguisher bottle, preventing the corrosion problems caused by corrosive media in traditional methods. It also provides more accurate and faster leak location, significantly reducing the influence of human factors in measurement; this method has strong scalability, requiring only minimal modifications to cover other products requiring similar airtightness testing. This invention utilizes integrated multi-parameter real-time dynamic acquisition and intuitive dynamic waveform display, enabling the detection of fire extinguisher bottle airtightness under various complex environments. By coupling factors such as temperature and altitude, it provides reference and guidance for subsequent equipment performance assurance, reducing testing costs and possessing significant promotional value.

[0085] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology, characterized in that, It includes a gas source system (1), a gas pressure pipeline (2), a pressure vessel chamber (3), a measurement and control system (4), an audio acquisition system (5), and an equipment operating console (6); Fire extinguisher cylinders (0) are installed inside the pressure vessel chamber (3). The gas source system (1) is connected to the fire extinguisher cylinders (0) inside the pressure vessel chamber (3) through the gas pressure pipeline (2). The audio acquisition system (5) is installed in the pressure vessel chamber (3). The equipment operating console (6) and the audio acquisition system (5) are both connected to the measurement and control system (4). The air supply system (1) is used to provide clean compressed air, including an air compressor (7), a filter (8), a desiccant (9), an air tank (10), and a pressure relief valve (11); The pressure vessel chamber (3) is equipped with a pressure sensor (14) and an audio acquisition system (5). The audio acquisition system (5) consists of multiple sound sensors installed in different locations within the pressure vessel chamber (3). The measurement and control system (4) includes a data acquisition unit and a measurement and control terminal, which consists of an industrial computer and a PLC controller; the measurement and control system (4) adjusts the speed of the air compressor (7) by controlling the strength of the electrical signal; The device control panel (6) is used to digitally display and waveform display the real-time pressure signal and sound signal of the measurement and control system (4), and can independently set the alarm threshold; By monitoring the pressure changes inside the fire extinguisher bottle (0) and the pressure vessel chamber (3) during the inflation process, the purpose of testing the airtightness of the fire extinguisher (0) is achieved; at the same time, the specific leak location of the fire extinguisher bottle (0) is located by analyzing the sound signals generated when the fire extinguisher bottle (0) leaks.

2. The non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology according to claim 1, characterized in that, The gas generated by the air compressor (7) enters the air storage tank (10) directly through the air pressure pipeline (2). The air storage tank (10) is equipped with a pressure relief valve (11). The filter (8) consists of a C-level filter (12) and an A-level filter (13). The gas output from the air storage tank (10) passes through the C-level filter (12), the desiccant (9), and the A-level filter (13) in sequence to separate free oil and water droplets in the air and dry the air. The purified air contains ≤1ppm oil, ≤0.1μm dust particles, and has a dew point temperature of -70℃.

3. The non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology according to claim 1, characterized in that, The air compressor (7) has a built-in controller with a linkage control mode. It uses a PID algorithm and vector frequency conversion precision control technology to receive remote control commands through a communication bus. The pressure relief valve (11) is passively controlled. The desiccant dryer (9) requires a power supply for manual power-on settings.

4. The non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology according to claim 1, characterized in that, The acquisition unit includes multiple PLC acquisition channels and a communication module, used to acquire voltage signals, current signals, and discrete signals; to monitor the operating status of each part of the non-contact airtightness testing system, and to monitor the parameters that need to be measured on the fire extinguisher bottle (0) under test during the test; the measurement and control terminal is used to control the non-contact airtightness testing system, including an industrial computer and a PLC controller.

5. The non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology according to claim 1, characterized in that, The sound sensor is used to collect the sound of air leakage in the pressure vessel chamber (3). Then, through the pre-established analysis model and the algorithm of sound wave attenuation in the confined space, the air leakage location of the fire extinguisher bottle (0) is calculated and fitted according to the sound intensity at different locations. The gas pressure pipeline (2) is equipped with a flow sensor to measure the flow rate in the pipeline.

6. The non-contact airtightness testing system combining the dual-pressure difference method and sound source localization technology according to claim 1, characterized in that, In the main interface of the system's software testing, the test information area includes real-time curves and test parameters; the real-time curves show how the pressure value changes over time during the test, and these curves are generated and refreshed in real time. The test parameters interface allows you to customize the test process, including test phase selection, alarm settings, and leak calculation parameters. The test process operation area in the main interface of the software test includes alarm, unloading and test start functions; during the test, the real-time curve interface will generate a curve of the pressure change inside the bottle over time, including the pressure rise stage, holding stage, test stage and unloading stage. The automatic monitoring function includes automatic pressurization, pressure stabilization, pressure maintenance, pressure unloading, and real-time pressure monitoring; the fault diagnosis function includes leakage calculation to determine the leakage per unit hour.

7. A non-contact airtightness testing method combining the dual-pressure difference method and sound source localization technology, characterized in that, The non-contact airtightness testing system using the dual differential pressure method combined with sound source localization technology as described in any one of claims 1 to 6 includes the following steps: Step 1: Clean compressed air is supplied by the air source system (1) and introduced into the fire extinguisher bottle (0) in the pressure vessel chamber (3) through the air pressure pipeline (2); Step 2: The pressure sensor (14) inside the pressure vessel chamber (3) collects the internal pressure of the fire extinguisher bottle (0) in real time, and the audio acquisition system (5) collects the sound signal of air leakage inside the pressure vessel chamber (3). The collected data is transmitted to the measurement and control system (4). Step 3: The measurement and control system (4) analyzes the pressure signal collected by the pressure vessel chamber (3), combines the pressure-time decay curve, couples the effects of temperature and altitude, and refers to the pressure change inside the pressure vessel chamber (3) to simulate and calculate the gas pressure change inside the fire extinguisher bottle (0), and displays it through the equipment operating console (6). Step 4: The measurement and control system (4) uses an algorithm based on the distance attenuation of sound waves in a confined space to calculate and fit the sound signal collected by the audio acquisition system (5) to the location of the leak in the fire extinguisher bottle (0) according to the sound intensity at different locations and through a pre-established analysis model.

8. The non-contact airtightness testing method combining the dual-pressure difference method and sound source localization technology according to claim 7, characterized in that, The simulation calculation of the gas pressure change inside the fire extinguisher bottle (0) in step three specifically includes: measuring the internal pressure of the fire extinguisher bottle (0) and the internal pressure of the pressure vessel chamber (3). When the fire extinguisher bottle (0) leaks, the leaked gas enters the pressure vessel chamber (3), causing its internal pressure to rise. The leakage amount is calculated by measuring the pressure change inside the pressure vessel chamber (3) before and after the leak.

9. The non-contact airtightness testing method combining the dual-pressure difference method and sound source localization technology according to claim 8, characterized in that, The calculation of leakage includes calculating the leakage per unit hour, and the calculation method is as follows: Set the following parameters: Explosion-proof enclosure volume Initial pressure of pressure sensor Pressure sensor pressure at test completion The system starts working, and the fire extinguisher bottle (0) begins to fill. The current time when the test was completed. ; Converted to atmospheric pressure, the calculated leakage rate per unit hour is the gas volume: 。 10. The non-contact airtightness testing method combining the dual-pressure difference method and sound source localization technology according to claim 7, characterized in that, The pressure-coupled altitude and temperature conversion method uses Matlab data fitting, which can correct environmental parameters for different regions based on historical climate data, and can also correct the simulated target environment by combining the environment of the test site. ； in, For altitude, For temperature, The current air pressure. This is the standard atmospheric pressure at sea level.

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